The  D.  Van  NoStrand  Company 

intend  this  book  to  be  sold  to  the  Public 
at  the  advertised  price,  and  supply  it  to 
the  Trade  on  terms  which  will  not  allow 
of  reduction. 


DREDGES  AND  DREDGING 


BY 

CHARLES  PRELINI 

Author  of  "Earth  and  Rock  Excavation,"  "  A  Treatise  on  Tunneling,"  "Earth  Slopes, 

Retaining  Walls  and  Dams,"  Professor  of  Civil  Engineering  in 

Manhattan  College,  New  York 


82    ILLUSTRATIONS 


NEW  YORK 

D.  VAN   NOSTRAND  COMPANY 

23   MURKAY  AND   27   WARREN   STREETS 
1911 


Copyright,  1911, 

BY 
D.   VAN   NOSTKAND    COMPANY 


THE  SCIENTIFIC  PRESS 

ROBERT   DRUMMOND   AND   COMPANY 

BROOKLYN,    N.  Y. 


PREFACE 


IT  is  an  old  and  true  saying  that  "  of  making  many  books  there  is 
no  end,"  and  this  is  especially  true  in  regard  to  engineering  treatises, 
as  each  decade  brings  its  improvements,  and  practices  that  are 
in  vogue  one  year  are  almost  obsolete  within  a  few  years.  To-day, 
too,  there  is  a  great  demand  in  the  profession  for  books  on  practical 
subjects,  as  it  is  only  in  this  manner  that  the  young  man  is  able 
to  profit  from  the  experience  of  his  older  brother. 

It  is  a  singular  fact  that  nearly  every  man  feels  that  he  is  com- 
petent to  carry  on  a  job  of  earth  or  rock  excavation,  yet  there  is 
nothing  more  difficult  than  to  do  such  work  economically.  Man 
since  prehistoric  times  has  been  digging  into  mother  earth,  yet 
there  is  always  something  to  learn  regarding  excavation  work. 
The  last  word  will  never  be  said  on  the  subject.  In  this  treatise 
only  one  class  of  excavation  is  touched  upon,  namely,  dredging. 

If  one  needs  an  excuse  for  offering  to  the  profession  this  book, 
it  is  found  in  the  vast  importance  of  dredging  in  our  commercial 
life.  Not  only  are  there  millions  upon  millions  of  dollars  invested 
in  dredging  plants  and  outfits,  but  it  has  only  been  possible  to  con- 
struct and  use  vessels  of  great  tonnage,  owing  to  the  wonderful 
achievements  of  the  dredge  designers  and  the  engineers  and  con- 
tractors engaged  in  operating  such  machines. 

Then,  too,  great  canals  are  constructed  with  the  aid  of  dredges, 
large  areas  of  swamp  lands  are  reclaimed  for  the  use  of  man  with 
such  machines,  and  precious  metals  are  recovered  from  streams  or 
river  bottoms  with  their  aid. 

This  treatise  is  written  with  a  view  of  presenting  the  subject 
in  a  concise  and  logical  manner,  so  that  it  may  be  found  useful 
both  to  the  man  of  experience  and  to  the  beginner  or  student. 
Should  it  so  prove  the  author  will  feel  that  his  labor  has  not  been 
in  vain. 

The  thanks  of  the  author  are  due  Mr.  Daniel  J.  Hauer  for  many 
valuable  suggestions.  C.  p. 

Manhattan  College,  September,  1911. 

iii 

242294 


CONTENTS 


LIST  OF  ILLUSTRATIONS 

INTRODUCTION.     A  HISTORY  OF  DREDGES  AND  DREDGING. 


CHAPTER   I 
DREDGING  AND  DREDGES 1 

CHAPTER-  II 

SOID6  AND  THEIR  CHARACTERISTICS Q 

CHAPTER   III 
SOUNDINGS  AND  HYDRAULIC  SURVEYS 12 

CHAPTER   IV 

EXCAVATION   OF  SUBAQUEOUS  ROCKS.     GENERAL  DISCUSSION.     EXCAVA- 
TION BY  HAMMERING , 21 

CHAPTER   V 

EXCAVATION   OF  SUBAQUEOUS  ROCKS — Continued.     BY  BLASTING.     COM- 
PARISON OF  THE  Two  METHODS 29 

CHAPTER   VI 
EXCAVATION  OF  SUBAQUEOUS  ROCKS — Continued,     BY  A  LARGE  BLAST.  ...    '42 

CHAPTER   VII 
HINTS  ON  SELECTING  DREDGES  FOR  VARIOUS  WORK 50 

CHAPTER   VIII 
DREDGING  CREWS,  THEIR  QUARTERS,  AND  TENDERS  FOR  DREDGES < .     56 

CHAPTER   IX 
CLASSIFICATION  AND  CAPACITIES  OF  DREDGES.  . 


vi  CONTEXTS 

CHAPTER   X 

PAGE 

LADDER  OR  ELEVATOR  DREDGE.     GENERAL  DISCUSSION 68 

CHAPTER  XI 
SEA-GOING  LADDER  DREDGES 74 

CHAPTER  XII 

SEMI-SEA-GOING  STATIONARY  AND  HIGH-TOWER  LADDER  DREDGES 83 

CHAPTER  XIII 
HYDRAULIC  DREDGES.     GENERAL  DISCUSSION 94 

CHAPTER  XIV 
SEA-GOING  HYDRAULIC  DREDGES 105 

CHAPTER  XV 
HYDRAULIC  DREDGES  FOR  CHANNELS  AND  RIVER  IMPROVEMENTS 120 

CHAPTER  XVI 
UNIVERSAL  DREDGES 132 

CHAPTER  XVII 
STIRRING  DREDGES 140 

CHAPTER   XVIII 
PNEUMATIC  DREDGES. 147 

CHAPTER   XIX 
DIPPER  DREDGES.     GENERAL  DISCUSSION 151 

CHAPTER   XX 
DIPPER  DREDGES — Continued 161 

CHAPTER  XXI 
GRAB  DREDGES 168 

CHAPTER   XXII 
DESCRIPTION  OF  CLAMSHELL  DREDGES 178 


CONTENTS  vii 

CHAPTER  XXIII 

PAGE 

TRANSPORTATION  OF  THE  DEBRIS.     CONVEYORS,  BARGES,  ELEVATORS 185 

CHAPTER  XXIV 
METHODS  AND  COSTS  OF  RIVER  DREDGES. 204 

CHAPTER   XXV 

/    DREDGING  FOR  METALS 217 

CHAPTER  XXVI 
DREDGING  FOR  INDUSTRIAL  PURPOSES 233 

CHAPTER   XXVII 
DRY-LAND  DREDGING 245 

CHAPTER  XXVIII 
THE  COST  OF  OPERATING  DREDGES 253 

CHAlTER  XXIX 
COST  DATA.  .  260 


LIST   OF   ILLUSTRATIONS 


FIG. 

1,  2.  Methods  of  Laying  out  Triangulation  Points. 

3.  Scott  &  Godsir  Rockcutter. 

4.  Lobnitz  Rockcutter. 

5.  Saunder's  Machine  for  Subaqueous  Rock  Excavation. 

6.  Drilling  Platform  Used  on  the  Danube  River. 

7.  Ingersoll  Drilling  Scow. 

8.  Rand  Drilling  Boat. 

9.  Boat  with  Submerged  Caisson  for  the  Excavation  of  Rock  under  the  Rhine 

River. 

10.  Plan  of  Flood  at  Hell  Gate,  N.  Y. 

11.  Honeycombing  of  Flood  Rock  showing  the  Direction  of  Drill  Holes  in 

Galleries. 

12.  Plan  of  the  Ledge  of  Rock  at  Henderson's  Point. 

13.  Method  of  Excavation  Followed  at  Henderson's  Point. 

14.  Stone  Lifter  on  St.  Lawrence  River. 

15.  16.  Side  View  and  Part  of  the  Deck  Plan  of  the  Dredge  "  Villede  Rochefort." 

17.  Dredge  "  Pas-de-Calais." 

18.  Dredge  "Cadiz." 

19.  Dredge  for  the  Marne  Canal. 

20.  Dredge  for  the  Rhone  River  Propelled  by  Sprocket  Wheel. 

21.  Stationary  Ladder  Dredge. 

22.  Stationary  Ladder  Dredge  on  the  Fox  River,  Wis. 

23.  Dredging  Plant  Used  on  the  Fox  River,  Wis. 

24.  High  Tower  Ladder  Dredge  "City  of  Paris." 

25.  Allen  Scraper  Used  on  the  U.  S.  Dredge  "Manhattan." 

26.  Rotary  Cutter  at  the  End  of  Suction  Pipe. 

27.  28.  Cross-section  and  Side  View  of  the  Centrifugal  Pump  of  a  Hydraulic 

Dredge. 

29.  Hoppers  in  the  Hydraulic  Dredge  "  Nereus." 

30.  Sand  Pump  on  Dredge  "  Nereus." 

31.  Dredge  "Thomas." 

32.  Cross-section  of  the  Dredge  "Thomas,"  showing  Central  Pit  and  Lateral 

Hoppers. 

33.  Central  Portion  of  the  Dredge  "City  of  Rouen,"  showing  the  Single  Hopper 

Amidships. 

34.  Dredge  "  J.  Israel  Tarte." 

35.  Plan  and  Longitudinal  Section  of  the  Dredge  "  J.  Israel  Tarte." 

36.  Floating  Discharge  of  the  Dredge  "  J.  Israel  Tarte." 


x  LIST  OF  ILLUSTRATIONS 

FIG. 

38.  Cross-section  of  the  Dredge  "King  Edward  VII." 

37.  Deck  Plan  and  Longitudinal  Section  of  the  Dredge  "King  Edward  VII." 

39.  Dredge  "King  Edward  VII." 

40.  Dredge  "St.  Petersburg." 

41.  Longitudinal  Section  of  the  Dredge  "Montevideo." 

42.  Jandin  Method  for  Sinking  Tubular  Piers. 

43.  Plan  and  Elevation  of  Steel  Trusses  Reinforcing  the  Hull  of  the  Dredge 

"Chicago." 

44.  Side  and  End  Views  and  Deck  Plan  of  a  Small  Dipper  Dredge  with  Bank  Spuds. 

45.  Dipper  Dredge  of  Six  Cubic  Yards  Capacity. 

46.  The  Dipper  Dredge  "Independent." 

47.  Dipper  Dredge  "Majestic." 

48.  English  Grab  Bucket  Dredge. 

49.  South  American  Grab  Dredge. 

50.  Grab  Bucket  for.  Dredging  Through  Clay. 

51.  Grab  Buckets  for  Gravel  and  Boulders. 

52.  Orange  Peel  Bucket,  Open. 

53.  Orange  Peel  Bucket,  Closed. 

54.  Cooper  &  Holdsworth's  Single  Chain  Attachment. 

55.  Dredge  "Finn  MacCool." 

56.  Ten  Cubic  Yard  Clamshell  Bucket  of  the  Dredge  "Finn  MacCool." 

57.  Sectional  View  of  the  Clamshell  Bucket  "Arnold." 

58.  Dredge  "Champion." 

59.  Ladder  Dredge  with  Pipe  Conveyor. 

60.  Pipe  Line  Conveyor  of  the  Dredge  "  J.  Israel  Tarte." 

61.  Open  Hold  Barge. 

62.  Dumping  Scows  Used  at  Suez. 

63.  Dumping  Scows  for  Shallow  Water. 

64.  Sea-Going  Steam  Hopper. 

65.  Dumping  Scow  with  Sliding  Platform. 

66.  Sidewheel  Tugboat. 

67.  Screw-Propelled  Tug  Boat. 

68.  Bucket  Elevator  for  Unloading  Barges. 

69.  Floating  Elevator  for  Unloading  Barges. 

70.  Floating  Elevator  with  Double  Ladder. 

71.  Grab  Bucket  for  Unloading  Barges. 

72.  A  Placer  Dredge  with  Revolving  Screen. 

73.  Placer  Dredge  with  Shaking  Screens. 

74.  Placer  Dredge  with  Sluice  Box. 

75.  Plan  and  Elevation  of  a  Long  Sluice-Box. 

76.  Placer  Dredge. 

77.  Hydraulic  Sand  Dredge. 

78.  Ladder  Sand  Dredge. 

79.  Machine  for  Unloading  Sand  from  Barges. 

80.  Title  Lands  at  Seattle. 

81.  Bucket  for  Dry  Land  Dredging. 

82.  The  Austin  Drainage  Excavator. 


INTRODUCTION 


THE   HISTORY  OF  DREDGES  AND  DREDGING 

DREDGING  is  an  old  industry,  but  it  is  only  within  the  last  fifty 
years  in  Europe,  and  during  the  past  twenty-five  years  in  America 
that  rapid  advances  have  been  made  in  designs  and  types  of  machines, 
so  that  the  cost  of  dredging  has  been  materially  reduced.  It  is 
almost  impossible  to  give  an  accurate  history  of  the  industry  of 
dredging,  but  a  few  facts  can  be  given  that  may  be  of  interest  to 
the  student. 

No  doubt  the  ancients  used  some  primitive  forms  of  dredges, 
but  if  any  such  work  was  done  by  them  it  was  generally  near  the 
shore  and  was  in  most  cases  done  by  hand.  The  boats  used  by 
the  ancients  were  built  to  go  in  shallow  water,  so  that  there  was 
not  much  need  for  dredges.  It  may  be  of  interest  to  note  that 
even  to-day  some  dredging  is  done  by  hand.  (See  report  of  the 
Minister  of  Public  Works  of  Canada  for  year  ending  June  30,  1903.) 

The  first  forms  of  dredges  wrere  long-handled  scoops  operated 
by  hand  from  floating  platforms.  Then  a  windlass  or  drum  was  used 
to  aid  in  the  work,  and  then  scows  were  substituted  for  the  plat- 
forms or  rafts.  The  development  was  no  doubt  gradual,  although 
it  is  a  great  step  from  these  primitive  scoops  to  the  immense 
buckets  and  dippers  of  to-day. 

In  operating  the  early  scoop  dredges  it  was  found  that  the  work 
done  stirred  up  much  material  which  floated  away  when  there 
was  a  strong  current.  This  brought  into  use  methods  of  stirring. 

The  first  mention  of  a  rude  dredging  machine  is  by  a  writer 
named  Veranteus  in  the  year  1591.  The  first  power  dredge  was 
one  invented  by  a  Dutch  engineer,  one  Cornelius  Meyer,  in  1685.  It 
was  operated  by  horse  power,  and  was  used  in  constructing  some 
of  the  canals  and  dykes  of  Holland. 

xi 


xii  INTRODUCTION 

On  the  continent  of  Europe  the  first  elevator  or  ladder  dredge 
was  designed  and  patented  by  Savery  in  1718.  The  first  dredge  of 
this  type  in  England  in  1747.  Three  years  later  in  France  iron 
buckets  were  first  used  on  a  ladder  dredge.  In  1781  a  ladder  dredge 
was  built  in  England  and  operated  by  horse  power. 

The  first  steam  dredge  was  built  in  England  in  the  year  1796, 
the  engine  being  designed  by  the  inventor  James  Watt.  This  was 
followed  in  1804  by  a  machine  of  the  same  design,  only  heavier. 

Little  progress  was  made  in  dredge  designs  and  building  during 
the  first  half  of  the  19th  century.  During  this  time  there  was  built 
in  England  a  dredge  of  rather  unusual  design.  A  barge  or  scow  had 
two  movable  wings  at  the  stern  that  reached  if  desired  to  the  two 
banks  and  to  the  bottom  of  the  stream.  At  the  back  was  a  scraper 
that  loosened  the  dirt,  and  the  two  wings,  with  the  aid  of  the  current, 
swept  the  loosened  material  ahead  and  finally  deposited  it  at  the 
mouth  of  the  stream.  The  wings  formed  a  temporary  dam,  which 
gave  enough  head  to  force  the  scow  downstream.  Some  noteworthy 
work  was  done  with  such  dredges. 

The  first  hydraulic  or  suction  dredge  was  suggested  in  France  in 
1867,  which  was  really  the  beginning  of  the  construction  of  modern 
dredges.  In  1872  the  first  dredge  of  this  type  was  built  in  America. 
Cutters  were  first  placed  on  hydraulic  dredges  in  1878.  The  credit 
of  building  the  first  hopper  dredge  in  1861  is  given  to  England. 

The  dipper  type  of  dredge  was  not  originated  in  America,  but 
it  has  been  developed  in  the  United  States  and  is  considered  dis- 
tinctly an  American  dredge. 

In  the  last  few  decades  wonderful  strides  in  these  machines 
have  been  made.  From  small  buckets  operating  slowly,  buckets 
of  more  than  10  cu.yds.  are  used  with  a  pull  of  about  100.000  Ibs. 
being  exerted  on  the  dipper,  and  three  or  four  dips  made  per  minute. 
Likewise  the  depth  to  which  they  will  excavate  has  been  greatly 
increased. 

The  grapple  dredge  has  been  an  evolution  of  the  dipper  machine, 
and  as  its  distinguishing  feature  is  the  clamshell  or  orange-peel 
bucket,  it  is  evident  that  it  is  a  modern  machine. 

Since  1890  both  in  Europe  and  America  wonderful  advances 
have  been  made  in  all  types  of  dredges.  One  country  has  introduced 
a  design  while  another  has  developed  it  and  improved  upon  it. 

This  has  been  so  regarding  the  ladder  dredge  for  mining  pur- 
poses. In  the  sixties  much  experimental  dredging  for  gold  was 


INTRODUCTION  xiii 

| 

carried  on  in  New  Zealand,  with  the  result  that  the  ladder  dredge 

was  accepted  as  the  best  type  for  the  purpose.  Within  a  short  time 
the  ladder  dredge  was  introduced  in  Western  United  States  for 
gold  mining,  and  to-day  the  dredges  used  in  California  are  said  to 
excel  all  others  in  use  for  gold  mining  throughout  the  world.  It 
has  only  been  within  twelve  years  that  the  tailing  stacker  has  been 
used  in  connection  with  these  dredges.  This  device  has  greatly 
simplified  the  work  and  materially  reduced  the  labor  needed 
to  operate  the  machine. 


A  TREATISE 

ON 

DREDGES  AND  DREDGING 

V 

CHAPTER  I 
DREDGING   AND   DREDGES 

DREDGING  is  the  operation  of  excavating  soils  from  the  bottom 
of  'bodies  of  water.  It  is  undertaken  for  different  purposes,  chiefly  for 
deepening  and  widening  the  bed  of  rivers  and  navigable  channels,  or 
for  deepening  harbors  and  bays  to  facilitate  navigation,  or  preparing 
the  foundations  of  immense  masonry  structures,  which  should  be 
located  directly  on  ledge  rock,  usually  encountered  far  below  the  bed 
of  the  stream.  To-day  dredging  is  also  undertaken  for  mining  and 
other  industrial  purposes,  as  will  be  shown  later.  No  matter  for 
what  reason  these  dredging  operations  are  undertaken,  they  are 
always  made  by  powerful  machines  called  Dredges  in  America  and 
Dredgers  in  England,  built  with  an  efficiency  proportionate  to  the 
magnitude  of  the  improvement  upon  which  they  are  employed. 

Engineers  and  public  officials  frequently  do  not  realize  the 
importance  of  dredging.  Vast  sums  of  money  are  being  spent 
for  this  class  of  work  and  new  projects  are  continually  being  placed 
before  the  public  that  involved  dredging.  Even  manufacturers 
of  dredging  machinery  do  not  seem  to  comprehend  the  future  great 
development  of  this  industry,  as  dredges  are  the  means  of  handling 
large  quantities  of  raw  materials  as  well  as  of  making  extensive 
excavations  both  on  land  and  under  water. 

The  principal  uses  of  dredging  machinery  may  be  grouped 
as  follows: 


A  TREATISE  ON  DREDGES   AND   DREDGING 

Channels : 

Deepening  and  widening  channels  through  bays  and  rivers. 

Harbors : 

Cleaning  out  harbors. 
Building  new  harbors. 
Enlarging  old  harbors. 

Rivers : 

Straightening  rivers. 

Removing     obstructions,    as    sandbars,     deposits    of    mud, 

sawdust,  etc. 
Building  dykes  and  levees. 

Canals  and  ditches: 
Navigation. 
Drainage. 
Irrigation. 
Power. 

Reservoirs  and  dams: 

Cleaning  out  debris  and  deposits  of  vegetable  matter. 

Reclaiming : 
Low  ground. 

Filling  behind  bulkheads  and  piers. 
Flooding  land  to  dredge  it. 

Mining : 

Gold  from  rivers. 

Gold  from  placer  deposits. 

Platinum. 

Tin. 

Marl  for  cement  industry. 

Clay  for  bricks  and  pottery. 

Phosphate  rock  for  fertilizer. 

Sand: 

For  building  purposes. 
For  glass  industry. 
Magnetic  sand. 

Gravel : 

For  many  purposes. 
Foundation  work. 


DREDGING  AND  DREDGES  3 

Dredging  usually  involves  other  operations,  which  are :  The  hy- 
draulic survey  of  the  locality  to  be  improved,  the  knowledge  of  the 
quality  and  quantity  of  the  soil  to  be  excavated,  and  finally  the 
work  of  the  machines  used  in  the  excavation  of  the  materials  from 
the  bottom  and  of  those  employed  in  the  transportation  of  the 
debris. 

The  hydraulic  survey  is  easily  obtained  by  any  one  of  the  well- 
known  methods.  From  this  survey  a  chart  may  be  made  indicating 
the  depth  of  the  various  points  along  the  line  of  the  proposed  improve- 
ment. Knowing  the  depth  of  each  point  as  required  by  the  improve- 
ment, while  from  the  survey  is  learned  its  present  depth,  it  is  evident 
that  their  difference  will  represent  the  height  of  the  excavation  at 
such  a  point.  The  total  difference  of  all  the  points  will  give  the 
total  amount  of  material  to  be  excavated  in  order  to  obtain  the 
required  improvement. 

The  soils,  considered  from  the  point  of  view  of  the  cohesive 
force  of  their  particles,  may  be  broadly  divided  into  rocks  and 
loose  soils.  Rocks  are  those  in  which  the  force  of  cohesion  is  so 
great  that  great  power  is  necessary  in  order  to  separate  its  particles. 
Loose  soils  are  those  having  the  particles  united  by  such  slight 
cohesion  that  it  can  be  easily  overcome. 

In  dredging,  different  kinds  of  machines  are  used,  depending 
upon  the  quality  of  soils.  Solid  rock  must  first  be  reduced  to 
small  fragments,  so  as  to  be  readily  raised  to  the  surface.  The 
rock  is  usually  broken  in  two  different  ways,  by  hammering;  and 
by  blasting.  The  hammering  consists  in  attacking  the  rock  by 
means  of  successive  blows  struck,  with  great  violence,  while  in 
blasting  the  rock  is  shattered  by  the  mighty  force  of  dynamite 
or  other  explosive.  It  is  in  the  excavation  of  loose  soils  as  well 
as  for  picking  up  the  fragments  of  rock  broken  by  any  one  of  the 
methods  to  be  indicated,  that  the  dredging  machines  are  employed. 
These  are  divided  into  continuous  and  intermittent  types.  Contin- 
uous are  those  that  remove  continuously  the  material  from  the 
bottom,  while  intermittent  are  those  that  engage  the  material 
at  intervals. 

Dredges.  Continuous  dredges  are  of  four  different  types — the 
ladder,  the  hydraulic,  the  stirring,  and  the  pneumatic  dredges. 
The  ladder  dredge  excavates  the  bottom  by  means  of  a  series  of 
buckets  running  with  great  velocity  along  a  ladder.  The  buckets 
scrape  the  soil  at  the  bottom,  raise  the  debris  to  the  surface  and 


4  A  TREATISE  ON   DREDGES   AND   DREDGING 

discharge  it  into  barges  or  conveyors  so  as  to  send  it  to  its  final 
destination.  The  hydraulic  dredge  removes  the  material  from 
the  bottom  by  means  of  a  large  centrifugal  pump  which  draws  the 
materials,  mixed  with  water,  into  a  suction  tube  and  forces  them 
to  distant  points  by  means  of  a  long  line  of  pipes.  The  stirring 
dredges  are  those  employed  in  the  excavation  of  soils  composed 
of  very  finely  divided  particles;  they  agitate  the  soil  and  the  material 
thus  brought  in  suspension  is  carried  away  by  the  action  or  current 
of  water.  The  pneumatic  dredges  are  those  in  which  the  material 
from  the  bottom  is  forced  into  the  suction  tube  and  thence  into 
the  discharging  pipe,  by  the  action  of  continuous  jets  of  compressed 
air  turned  upward  into  the  tube. 

Intermittent  dredges  are  those  provided  with  a  single  bucket 
of  large  capacity,  by  means  of  which  the  material  at  the  bottom 
is  raised  to  the  surface  and  dumped  into  scows,  to  be  conveyed 
to  distant  points.  All  these  various  operations  are  made  by  the 
bucket  before  it  returns  to  the  bottom  to  once  more  engage  the 
material.  The  single-bucket  intermittent  dredges  are  of  two  different 
types,  the  dipper  and  the  grapple  dredges.  The  dipper  dredge 
is  similar  to  the  steam  shovel  used  in  land  work,  the  only  difference 
being  that  it  is  mounted  on  a  float,  and  the  bucket  is  usually  of 
larger  capacity.  The  grapple  dredge  is  provided  with  buckets  in 
the  shape  of  the  clamshell  or  of  the  orange-peel,  thus  originating 
two  principal  varieties  of  the  grapple  dredge,  known  as  the  clam- 
shell and  the  orange-peel  bucket  dredges;  These  machines  are 
also  mounted  on  floats  and  the  capacity  of  the  buckets  is  large. 

Transporting  Excavated  Materials.  The  materials  raised  from  the 
bottom  oif  the  water  are  transported  to  their  final  dumping  place 
by  various  methods.  In  the  sea-going  hopper  dredges  the  materials 
are  stored  in  large  bunkers  and  are  carried  to  the  dumping  place 
on  board  of  the  same  steamer  carrying  the  excavating  machinery. 
The  debris  can  also  be  conveyed  by  means  of  belt  conveyors  or 
pipes,  or  transported  on  floats  and  barges  with  closed  bottoms 
from  which  the  materials  are  raised  again  by  some  device  and  sent  to 
their  destination,  or  the  scows  are  self-dumping,  discharging  the 
debris  into  the  deep  water  by  simply  opening  the  gates  forming  the 
floor  of  the  scows. 

A  thorough  knowledge  of  the  various  soils  and  machines  is 
necessary  for  successful  dredging;  and  this  depends  exclusively 
upon  the  fact  that  the  best-suited  machine  should  be  used  for  the 


DREDGING  AND  DREDGES  5 

removal  of  a  certain  kind  of  soil.  In  dredging,  the  greatest  attention 
should  be  given  by  engineers  and  contractors  to  the  selection  of 
the  machines,  which  should  be  the  most  efficient  and  economical 
for  the  improvement  under  consideration.  Such  a  selection,  however, 
should  be  the  result  of  a  thorough  knowledge  of  both  the  various 
excavating  and  transporting  machines  at  their  disposal,  and  the 
kind  of  soil  to  be  removed. 


J 

CHAPTER  II 
SOILS   AND   THEIR   CHARACTERISTICS 

IN  considering  any  harbor  or  river  improvement  necessitating 
the  employment  of  dredges,  as  previously  shown,  it  is  important 
to  carefully  examine  the  nature  of  the  soil  to  be  excavated.  Such  a 
study  will  influence  the  selection  of  the  machines  and  the  arrange- 
ment of  the  work.  By  using  the  most  efficient  machines  and  arrang- 
ing the  work  in  the  most  convenient  way  the  improvement  under 
consideration  will  be  done  in  the  most  economical  manner,  namely 
at  the  smallest  cost.  Hence  the  great  importance  of  a  thorough, 
knowledge  of  the  soil  to  be  excavated. 

It  would  be  impossible  to  describe  all  the  various  soils  that 
may  be  encountered  in  dredging.  They  are  found  in  so  many  varieties 
and  so  mixed  together  that  it  is  difficult  to  trace  each  to  its  respective 
group.  However,  for  sake  of  classification  only  the  most  character- 
istic soils  will  be  reviewed  here,  indicating  the  type  of  dredge  con- 
sidered the  most  appropriate  for  working  in  each  soil.  The  soils 
will  be  reviewed  in  the  following  order:  Rock,  disintegrated  rock 
and  conglomerates,  gravel,  hardpan,  clay  and  loam,  sand  and  silt. 

Rock.  The  ordinary  dredging  operations  usually  consist  of 
clearing  the  bottom  of  canals,  rivers,  bays,  harbors,  etc.  Since 
these  basins  are  formed  by  alluvial  deposits  accumulated  there  for 
centuries,  as  a  rule,  they  form  strata  of  great  thickness,  and  solid 
rock  is  very  seldom  encountered.  But  even  in  the  few  cases  in 
which  rock  is  found,  owing  to  the  fact  that  for  a  long  time  it  has 
been  exposed  to  the  destructive  action  of  fresh  or  salty  water,  it  is 
generally  found  in  such  a  disintegrated  condition,  as  to  be  consid- 
ered a  loose  soil  instead  of  real  rock.  However,  in  removing  obstruc- 
tions to  navigation  or  in  widening  and  deepening  harbors  and 
channels,  solid  ledges  of  rock  are  encountered.  It  is  removed,  as 
stated,  either  by  hammering  or  blasting. 

Disintegrated  Rock  and  Conglomerates.  The  rock  that  has 
been  disintegrated  by  the  action  of  water  or  other  means  and  still 

6 


SOILS  AND  THEIR  CHARACTERISTICS  7 

preserve  great  compactness,  as  well  as  the  conglomerates  or  pudding- 
stones,  which  consist  of  pebbles  held  together  by  some  natural 
cement,  are  difficult  to  remove  from  the  bottom  of  water.  Their 
removal,  however,  may  be  successfully  obtained  by  hammering 
or  even  by  blasting  or  otherwise,  by  powerful  dredges  in  which 
the  buckets  are  provided  with  strong  steel  teeth.  It  is  in  the  disin- 
tegrated and  soft  rocks  that  the  method  of  breaking  the  material 
by  hammering  is  considered  the  most  economical.  In  many  instances, 
disintegrated  rock  has  been  successfully  broken  by  hammering. 
Of  the  different  types  of  dredges,  the  one  that  gives  the  best  result 
in  digging  through  disintegrated  rock  and  conglomerates  is  the 
dipper  dredge;  although  those  of  the  clamshell  and  ladder  types 
have  also  been  employed  with  advantage.  The  bucket  of  the  dipper 
dredge  used  in  these  soils  is  armored  with  four  strong  steel  teeth. 
These  are  forced  into  the  conglomerate  or  disintegrated  rock  and  by 
pulling  up  the  bucket  the  material  is  dislodged  and  the  de*bris  fall- 
ing into  the  bucket  is  raised  to  the  surface.  But  when  these  compact 
materials  are  encountered  at  such  a  depth  that  the  dipper  dredge 
cannot  work  to  advantage,  both  the  ladder  and  clamshell  dredges 
are  found  more  adaptable.  When  the  ladder  dredge  is  used  the 
buckets  are  provided  with  strong  steel  teeth  and  the  endless  chains 
driving  the  buckets  are  run  with  great  velocity  in  order  that 
the  teeth  may  engage  the  compact  material  with  great  force.  By 
means  of  a  ladder  dredge  with  armored  buckets  even  large-sized 
stones  can  be  removed  from  the  bottom.  Thus  stones  of  over 
1  cu.m.  were  picked  up  by  the  buckets  of  a  ladder  dredge  in  the 
harbor  of  Dunkerque  in  the  English  Channel.  When  the  clam- 
shell dredge  is  used  the  bucket  is  either  entirely  formed  by  strong 
tines  or  the  edges  of  the  bucket  are  provided  with  tines.  The  grab 
bucket  lowered  to  the  bottom  at  great  speed  will  strike  the  rock 
with  force  and  the  tines  will  penetrate  into  the  mass.  By  closing 
the  bucket  the  rock  will  be  broken  and  the  debris  will  thus  be  raised 
to  the  surface. 

Gravel.  Gravel  is  a  soil  chiefly  composed  of  small  hard  water- 
worn  smooth  fragments  of  rock  ordinarily  mixed  with  sand.  When 
gravel  is  encountered  in  thick  layers  at  the  bottom  of  rivers  or 
bays,  it  is  generally  a  very  compact  material,  so  as  to  be  considered 
almost  as  hard  as  any  conglomerate.  However,  when  it  is  attacked 
by  the  strong  teeth  of  the  buckets  of  dredges  of  various  types,  and 
a  furrow  has  been  dug  through  the  bank,  the  small  round  pebbles 


8  A  TREATISE  ON  DREDGES  AND   DREDGING 

become  very  loose  and  are  then  easily  removed  by  means  of  any 
ordinary  dredge.  The  ladder  dredge,  with  its  buckets  that  are 
continuously  scraping  the  loosened  pebbles  of  the  bank  of  gravel, 
thus  filling  up  the  buckets  to  their  full  capacity,  seems  to  be  the 
most  efficient  machine  in  this  soil.  The  dipper  and  grapple  dredges, 
however,  are  found  very  efficient  machines  for  dredging  through 
gravel. 

Hardpan.  Hardpan  is  a  soil  composed  of  loam  and  boulders 
and  is  considered  very  compact  and  resistent.  Sometimes  it  is 
encountered  in  such  a  hardened  condition  as  to  be  considered  almost 
a  conglomerate  in  which  the  cementing  material  is  loam.  Hard- 
pans  are  met  in  numberless  varieties,  being  christened  by  contractors 
with  the  strangest  names.  In  the  reports  of  public  works,  when 
the  name  of  an  unknown  soil  is  mentioned,  as  a  rule  one  may  rest 
assured  that  is  a  variety  of  hardpan.  Only  three  types  of  dredges 
can  be  used  with  advantage  in  this  kind  of  soil,  and  they  are  the 
dipper,  the  grapple  and  the  ladder  dredges,  in  which  the  buckets 
are  provided  with  strong  steel  teeth.  The  most  efficient  machine  for 
digging  through  hardpan  at  shallow  depths  is  certainly  the  dipper 
dredge.  The  large  heavy  bucket  easily  penetrates  through  the 
soil  and  being  of  large  dimensions  may  loosen  and  lift  boulders 
of  any  size.  The  grab  dredge,  provided  with  a  clamshell  bucket 
in  which  the  edges  are  furnished  with  strong  tines  may  be  found 
very  convenient,  especially  when  dredging  through  hardpans  located 
at  a  certain  depth  from  the  surface  of  water.  The  ladder  dredge 
in  which  the  buckets  are  armed  with  steel  teeth  for  the  double 
purpose  of  breaking  the  loam  and  facilitating  the  picking  up  of 
the  boulders,  can  also  be  used  for  dredging  through  hardpan.  In 
this  soil,  however,  the  ladder  dredge,  in  some  cases,  may  not  be 
found  so  advantageous  as  the  two  other  types  of  machines,  owing 
to  the  fact  that  the  buckets,  no  matter  how  large,  may  be  too  small' 
for  raising  the  boulders,  especially  when  of  large  dimensions.  Large 
boulders  may  entangle  the  buckets  and  disarrange  the  machine. 

Clay  and  Loam.  Clay  and  loam  are  as  a  rule  considered  among 
the  loose  soils,  and  yet  they  are  the  worst  kind  of  such  materials 
to  remove.  They  stick  to  the  buckets  and  cause  a  great  deal  of 
trouble.  All  the  different  types  of  dredges  can  be  used  with  more 
or  less  advantage.  The  dipper  and  grapple  dredges  are  considered 
the  most  efficient.  With  these  machines  the  impact  of  the  buckets 
in  attacking  the  soil  permits  of  easy  penetration,  thus  rilling  the 


SOILS  AND  THEIR  CHARACTERISTICS  9 

buckets  to  their  utmost  capacity.  But  after  the  material  has  been 
raised  to  the  surface  it  takes  some  time  to  unload  the  bucket,  as 
the  clay  sticks  to  the  sides  and  falls  off  with  great  difficulty.  The 
ladder  dredge  is  also  adaptable  to  these  soils,  but  the  buckets  must 
be  of  special  construction  to  permit  them  to  scrape  into  the  bank  of 
clay  and'  be  filled  with  the  material,  instead  of  sliding  upon  the 
surface  of  the  bank ;  the  buckets  are  provided  with  a  sharp  edge  in 
the  shape  of  a  beak.  After  the  buckets  have  dumped  their  contents 
they  must  remain  exposed  as  long  as  possible  to  the  air  in  order 
that  the  particles  of  clay  sticking  to  the  buckets  may  be  partially 
dried.  To  facilitate  this  exposition  to  the  air  the  buckets  are  run 
at  very  low  speed  and  the  tower  supporting  the  revolving  guiding 
drum  is  located  as  high  as  possible  upon  the  frame  of  the  boat. 
The  hydraulic  dredges  are  the  machines  most  extensively  employed 
to-day  for  dredging  through  clay  and  loamy  soils.  But  in  order  to 
cut  the  material  so  as  to  be  in  condition  to  be  drawn  through 
the  suction  pipe  and  pass  through  the  centrifugal  pump,  the 
lower  end  of  the  suction  pipe  is  provided  with  a  cutter  or 
agitator. 

Sand.  Sand  is  one  of  the  most  common  materials  encountered 
in  dredging.  The  greatest  harbor  and  river  improvements  so  exten- 
sively undertaken  to-day  throughout  the  world  chiefly  consist  in 
removing  sandbars  along  the  estuaries  of  large  rivers  or  seashores. 
Sand  is  found  in  different  forms  depending  upon  the  mineral  from 
which  it  originated.  Generally  speaking  the  sand  is  formed  by 
the  grains  of  materials  rubbing  one  against  another  as  they  are 
moved  onward  in  brooks  and  rivers  or  pushed  backward  and  for- 
ward by  the  waves  on  a  seabeach.  Only  the  hardest  materials 
that  resist,  such  a  destructive  action  can  produce  sand,  and  for 
this  reason  it  is  usually  found  derived  from  quartz;  the  particles 
of  softer  materials  are  rapidly  ground  into  mud.  Sands  are  classified 
as  coarse  and  fine,  a  distinction  based  upon  the  size  into  which 
their  particles  have  been  reduced.  Coarse  sands  can  be  easily 
removed,  even  if  they  are  mixed  with  gravel  and  shells,  while  it 
is  more  difficult  to  remove  the  fine  sands,  owing  to  the  fact  that 
the  finely  divided  particles  tend  to  float.  An  example  of  the  different 
efficiency  of  dredging  through  these  two  varieties  of  the  same  material 
is  quoted  by  Mr.  Henry  Satre.  He  says  that  a  dredge  employed 
in  the  improvement  of  the  Harbor  of  Cette,  France,  used  to  remove 
*  180  cu.m.  por  hour  of  coarse  sand  mixed  with  algae,  while  it  could 


10  A  TREATISE  ON  DREDGES  AND  DREDGING 

not  excavate  more  than  45  cu.m.  per  hour  when  very  fine  sand 
was  encountered. 

The  hydraulic  dredge  is  the  machine  used  to  the  best  advantage 
in  dredging  through  sand.  The  dipper  and  grapple  dredges  are 
objectionable  owing  to  the  fact  that  the  fine  material  will  easily 
escape  through  the  seams  of  the  bucket  and  consequently  only  a 
very  limited  amount  of  material  will  be  removed  at  each  lift  of 
the  bucket.  The  buckets  of  the  ladder  dredges,  in  parsing  over 
the  bank  of  sand  at  great  speed,  stir  up  the  material  to  such  an 
extent  that  a  large  quantity  of  water  will  be  taken  up  and  only  a 
small  percentage  of  sand  will  be  found  in  the  buckets.  The  raising 
to  the  surface  of  such  a  large  amount  of  water  decreases  the  efficiency 
of  the  machine  and  increases  the  cost  of  the  work  per  unit  of  volume. 
It  is  obvious  that  the  finer  the  particles  of  sand  are  the  larger  the 
quantity  of  water  will  be  in  the  buckets  of  the  ladder  dredges. 
Although  the  hydraulic  dredges  are  considered  the  best-adapted 
machines  for  dredging  through  sand,  yet  in  order  to  obtain  the 
proper  efficiency  from  these  machines,  the  end  of  the  suction  pipe 
must  be  provided  with  some  device  that  facilitates  the  separation 
of  the  coarse  sand  from  its  bank,  so  that  when  well  mixed  with 
water  will  be  easily  raised  through  the  suction  tube,  and  may  also 
prevent  the  floating  away  of  the  fine  sand  under  the  stirring  action 
of  the  pump. 

Mud  or  Silt.  Another  soil  which  is  very  extensively  encountered 
in  dredging  is  mud  or  silt.  This  is  composed  of  a  finely  powdered 
mineral  matter  mixed  with  organic  particles  derived  from  animal 
or  vegetable  sources,  the  powdered  minerals  being  the  result 
of  the  disintegration  of  soft  rock  by  water  and  other  natural  agents. 
The  particles  of  mud  are  so  infinitesimally  small  and  so  finely  divided 
they  are  carried  in  suspension  by  the  running  water,  and  are  deposited 
in  places  where  the  water  is  quieter.  Such  a  material  is  usually 
encountered  as  forming  the  bottom  of  the  mouth  of  rivers,  bays 
and  harbors.  The  particles  of  mud  are  so  finely  divided  they  do 
not  run  away  as  easily  as  sands,  but  stick  together  in  such  a  way 
that  they  can  be  removed  with  greater  facility. 

Dredges  of  any  description  may  be  used  with  advantage  for 
the  removal  of  mud.  The  dipper  and  grab  dredges  are  found  very 
useful  for  dredging  through  mud,  especially  when  buckets  of  large 
capacity  are  employed.  The  ladder  dredge  also  is  considered  a 
very  efficient  machine  in  this  kind  of  soil.  The  rapid  movement 


SOILS  AND  THEIR  CHARACTERISTICS  H 

of  the  buckets  will  tend  to  stir  up  the  material  to  such  an  extent 
that  its  light  particles  may  become  loose  again  and  float  all  around 
the  point  of  excavation.  To  avoid  this  the  chain  buckets  are  run 
at  a  very  low  speed.  As  this  reduces  the  efficiency  of  the  machine 
it  is  overcome  by  using  buckets  of  very  large  capacity.  The  hydraulic 
dredge,  although  very  good  in  this  kind  of  soil,  has  the  disadvan- 
tage of  stirring  up  the  material  to  such  an  extent  that  it  is  mixed 
with  a  very  large  amount  of  water.  Thus  an  enormous  amount 
of  power  is  required  to  remove  a  comparatively  small  amount  of 
material.  The  large  amount  of  water  diluting  the  mud  is  considered 
an  advantage  when  the  de"bris  is  used  to  fill  up  low  lands,  as  the 
water  facilitates  the  equal  distribution  of  the  material  over  a  larger 
area.  On  the  other  hand  this  surplus  water  is  a  hindrance  when  the 
material  is  pumped  into  the  hold  of  the  dredge  to  be  carried  to  the 
dumping  place,  as  in  the  hopper  type. 


CHAPTER  III 
SOUNDINGS   AND   HYDRAULIC  SURVEYS 

IN  order  to  estimate,  even  in  an  approximate  way,  the  time 
and  cost  of  a  contemplated  job  of  dredging,  it  is  necessary  to  make 
an  accurate  survey  of  the  locality.  This  should  indicate  the  shore 
lines,  soundings,  obstruction  to  navigation  as  bars,  sunken  ledges, 
boulders,  etc.,  giving  all  the  data  from  which  can  be  obtained  a  thor- 
ough knowledge  of  the  place  of  the  contemplated  improvement. 
From  this  survey  is  deduced  the  amount  of  material  to  be  removed 
from  the  bottom,  in  order  to  obtain  the  required  depth  of  water; 
and  from  the  amount  of  material  is  calculated  also  the  cost  and 
time  required  for  the  proposed  work. 

Any  hydraulic  survey  consists  of  two  distinct  operations,  namely, 
the  measuring  of  the  depth  of  water  at  various  points  and  the  location 
of  the  different  points  where  the  soundings  are  made. 

Soundings.  Soundings  are  made  in  -three  different  ways:  (a) 
by  means  of  graduated  rods,  (6)  by  lead  lines,  (c)  by  automatic 
apparatus. 

(a)  Soundings  are  made  by  means  of  graduated  rods  which 
while  resting  on  the  bottom  are  kept  vertical  by  the  operators, 
who  read  directly  the  depth  of  water  at  each  point.  The  operators,  in 
small  boats,  go  all  over  the  part  of  the  harbor  or  river  to  be  improved, 
while  the  different  points  are  located  by  any  one  of  the  various 
methods  to  be  explained.  Owing  to  the  limited  length  of  the  grad- 
uated rods,  this  manner  of  making  soundings  is  only  applicable 
to  localities  with  very  shallow  waters,  and  it  is  not  accurate. 

(6)  Soundings  are  more  commonly  made  by  means  of  a  lead  line. 
This  consists  in  lowering  a  weight  of  10,  15  or  20  Ibs.  of  lead  attached 
to  a  graduated  rope.  The  lead  is  shaped  like  the  frustrum  of  a  cone 
with  the  base  hollowed  out  to  hold  some  grease.  The  soil  of  the 
bottom  adheres  to  the  grease,  and  thus  shows  the  nature  of  the 
excavation,  which  information  should  be  entered  in  the  field  book 
and  marked  upon  the  map.  The  sounding  line  is  made  of  strong 

12 


SOUNDINGS  AND  HYDRAULIC  SURVEYS  13 

cord  and  divided  into  feet  by  different  colored  rags  or  other  visible 
marks.  Since  the  cord  is  liable  to  change  its  length  it  should  be 
compared  from  time  to  time  with  some  standard  measure.  Com- 
parative tests  of  the  two  methods  of  soundings  were  made  by  Col. 
G.  L.  Gillespie,  U.  S.  A.  Corps  of  Engineers,  in  the  harbor  of  New 
York,  where  part  of  the  ground  had  been  gone  over  by  both  methods. 
He  found  that  the  rod  soundings  showed  a  less  depth  than  the  line 
soundings  by  an  average  of  six  inches.  In  these  experiments  a 
14-lb.  lead  was  used  and  the  line  was  compared  at  frequent  intervals 
with  a  steel  tape  in  order  to  verify  its  accuracy  and  when  not  in 
use  was  kept  lying  in  fresh  sea  water. 

(c)  To  make  soundings  by  any  one  of  the  two  methods  just, 
explained  requires  some  length  of  time;  to  proceed  more  rapidly 
automatic  soundings  were  devised.  These  consist  either  of  a  grad- 
uated rod  or  a  sweep.  In  both  cases  the  lower  end  of  the  apparatus 
is  kept  resting  on  the  bottom,  while  the  depth  of  the  various  points 
is  recorded  automatically. 

On  the  Delaware  River  at  Philadelphia  the  soundings  were 
.made  from  a  long  raft  by  means  of  a  weighted  wooden  sounding 
rod,  the  raft  being  shifted  transversely  to  its  length,  for  successive 
rows  of  soundings,  by  long  anchor  cables.  The  method  of  the  sweep 
was  found  of  more  practical  application.  Thus  in  the  same  work 
at  Philadelphia  was  used  a  short  horizontal  sweep  which  was  passed 
over  the  bottom;  the  sweep  was  either  held  by  vertical  gauge  rods 
attached  to  a  boat  which  was  rowed  over  the  ranges,  or  it  was  manipu- 
lated by  a  diver  working  from  a  scow  in  tow  of  a  tug. 

Based  on  the  same  principle  of  a  sweep  bar,  a  new  device  for 
recording  automatically  the  various  soundings  was  constructed 
by  Mr.  R.  M.  Pardessus  and  described  in  the  Eng.  News,  Vol.  XLIX. 
The  apparatus  is  carried  by  a  barge  which  is  moved  along  fixed 
ranges  in  tow  of  a  tug  at  uniform  speed.  The  sounding  is  made 
by  a  transverse  sweep  bar  fastened  to  the  outer  ends  of  two  arms, 
which  are  pivoted  one  on  each  side  of  the  barge  and  extend  rear- 
wardly  down  into  the  water.  The  sweep  is  made  of  a  piece  of  rail- 
road rail  to  give  the  necessary  weight.  At  the  upper  end  of  the 
hinged  arms  is  a  recording  apparatus  which  marks  the  profile  of 
the  bottom  on  a  strip  of  paper  moved  by  clock-work.  The  speed 
of  the  tug  and  the  motion  of  the  paper  being  adjusted  to  a  known 
ratio,  the  curve  traced  on  paper  is  a  scale  profile  of  the  bottom 
along  the  range  over  which  the  sounding  barge  is  towed. 


14  A  TREATISE   ON  DREDGES   AND   DREDGING 

The  Survey.  The  second  important  opeiation  required  in 
hydraulic  survey  is  the  correct  determination  of  the  points  where 
soundings  were  made.  This  is  obtained  in  three  different  ways, 
which  are:  first,  by  triangulation  from  shore  stations;  second, 
by  sextant  observations  from  the  boat;  third,  by  running  the 
boat  over  known  ranges  and  spacing  the  soundings  by  time. 

First.  The  location  of  the  various  points  where  soundings  were 
made  is  determined  very  correctly  by  means  of  triangulation  from 
shore  stations.  A  base  line  is  selected  along  the  shores  so  as  to 
command  a  large  view  of  the  locality  to  be  surveyed.  The  line  is 
correctly  measured  either  directly  or  by  triangulation.  At  the 
extreme  ends  of  the  base  line  are  set  up  two  transits,  with  very 
distinct  graduation,  in  order  to  make  angle  readings  very  promptly 
when  signals  are  given.  The  operators  take  simultaneous  "shots  " 
or  readings  of  the  angles  at  the  same  instant  that  the  soundings 
are  made.  These  are  obtained  by  means  of  conventional  signals 
from  the  men  in  the  boat,  who  indicate  the  moment  that  the 
readings  should  be  taken. 

Second.  Soundings  are  located  also  by  sextant  observations 
by  the  men  in  the  boat.  For  this  purpose  three  points  are  selected 
on  land,  such  as  can  be  seen  along  the  line  of  the  improve- 
ment to  be  surveyed  and  whose  geographical  position  has  been 
correctly  determined.  Soundings  are  made  by  a  surveying  party 
on  a  boat  running  with  a  velocity  of  1^  or  2  miles  per  hour;  while 
the  location  of  the  various  points  is  determined  by  reading  with 
sextants  the  angles  that  the  boat  makes  with  the  three  land  points. 
This  method  is  now  extensively  used  by  the  U.  S.  Coast  and  Geodetic 
Survey  and  it  is  based  upon  a  simple  principle  of  geometry. 

Let  L}  C,  R  (see  Fig.  1)  be  the  three  fixed  land  points  and  P 
the  unknown  position  of  the  boat.  The  angles  A  and  B  ar,e  read 
with  sextant. 

Draw  two  circles,  one  passing  through  LJ  P  and  C,  and  the 
second  through  C,  P,  R.  Now  from  geometry  it  is  known  that 
by  connecting  any  point  of  the  circumference  with  two  other  fixed 
points  on  the  same  circumference,  the  angle  will  be  constant.  The 
two  circles  intersect  at  the  points  C  and  P,  and  since  C  is  one  of 
the  fixed  points,  so  there  is  but  one  point  P  where  it  is  possible  to 
have  the  angle  C,  P,  R=A  and  C,  P,  L=B.  Therefore  these  two 
angles  determine  the  position  of  P. 

By  setting  off  on  a  three-armed   protractor  the  two  angles  A 


SOUNDINGS  AND  HYDRAULIC  SURVEYS 


15 


and  B  and  shifting  it  until  the  plotted  position  of  the  points  R, 
C  and  L  are  each  on  the  edge  of  an  arm,  the  center  of  the  protractor 
will  be  on  the  point  of  sounding  where  the  angles  were  taken.  There 
is  but  one  exception  to  this  rule ;  that  is,  when  the  point  P.  is  on  the 
same  circumference  passing  through  R,  C  and  L ;  then  its  position 
is  indeterminate  (see  Fig.  2);  generally  when  signals  are  from  3 
to  5  miles  the  angles  read  within  2  or  3  minutes  of  their  correct 
value,  the  point  can  be  plotted  within  5  or  6  ft.  of  its  true  position. 
This  is  sufficiently  accurate  for  hydrographic  work,  for  on  any  scale 
smaller  than  7-^-5-5-  5  or  6  ft.  is  not  a  hair  breadth  and  very  few 
charts  are  on  a  scale  larger  than  this. 


FIG.  1. 


FIG.  2. 


t  v 

Third.  Another  method  is  by  running  a  boat  over  a  known  range 
at  a  certain  speed  and  taking  soundings  every  1,  2  or  5  minutes, 
or  at  intervals  depending  upon  the  importance  of  the  proposed 
improvement.  Thus,  for  instance,  if  a  boat  is  running  at  a  speed 
of  2  miles  per  hour  and  soundings  are  made  every  3  minutes,  they 
will  be  80  ft.  apart,  and  when  the  course  of  the  boat  is  known  it 
is  a  very  simple  matter  to  locate  the  various  soundings,  thus  obtain- 
ing a  survey  of  the  bottom. 

No  matter  which  method  is  used,  in  taking  and  locating  the 
soundings  it  is  evident  that  a  topographical  map  of  the  bottom 
can  be  easily  drawn  from  the  field  notes.  Great  care,  however, 
should  be  taken  in  reducing  the  soundings  to  an  ideal  level,  which 
is  generally  the  mean  low  water  mark.  Consequently  the  correct 
time  at  which  the  soundings  are  made  should  be  accurately  recorded 
so  as  to  compare  them  with  the  height  of  the  tide  at  that  time,  and 
all  the  soundings  reduced  to  a  common  plan,  which  is  the  surface 
of  the  mean  low  water. 

Measurement.  A  topographical  map  of  the  bottom  of  the  body 
of  water,  indicating  the  depths  of  various  points  of  the  bottom  from 
the  surface  of  the  water,  with  mean  low  water  as  a  datum  line,  is 


16  A  TREATISE  ON  DREDGES  AND   DREDGING 

made  from  the  field  notes.  Either  on  this  map  or  a  similar  one 
the  required  depths  are  marked,  hence  by  comparison  the  total 
depths  of  material  to  be  removed  are  easily  calculated.  A  series  of 
cross  sections  can  be  taken  at  some  distance  apart  and  thus  the 
volume  of  the  excavation  between  the  consecutive  cross  sections  is 
determined.  The  amount  of  cubic  contents  between  the  various 
cross  sections  will  give  the  total  amount  of  material  to  be  removed 
in  the  proposed  work.  The  manner  of  calculating  the  cubic  content 
between  the  consecutive  cross  sections  is  exactly  the  same  as  for 
land  work,  namely  by  the  mean  end  area  or  prismoidal  formula. 
Generally  only  the  former  method  is  used. 

Place  Measurement.  Engineers  have  two  methods  for  estimating 
the  amount  of  the  dredged  materials — by  place  measurement  and 
by  scow  measurement. 

When  specifications  state  that  the  amount  of  the  dredged  material 
will  be  measured  in  place,  it  means  that  it  will  be  deduced  from 
two  hydraulic  surveys  made,  one  before  the  work  begins  and  the 
second  after  the  improvement  has  been  completed.  The  difference 
between  these  two  surveys  will  represent  the  total  amount  of  material 
removed  to  obtain  the  required  improvement.  In  practical  work 
a  series  of  transverse  cross  sections  are  drawn  on  the  plan  of  the 
proposed  improvement,  extending  all  through  the  width  of  the 
work.  The  area  of  the  cross  sections  indicating  the  amount  of 
material  removed  is  given  by  the  difference  of  the  two  hydraulic 
surveys. 

Scow  Measurement.  The  second  method  of  determining  the 
amount  of  dredged  material  is  by  scow  measurement.  This  consists 
in  measuring  the  capacity  of  the  scows  or  boats  that  carry  away 
the  excavated  materials  and  deduce  the  total  amount  of  the  dredged 
material  from  the  number  of  boats  employed  in  transporting  the 
materials  to  the  dumping  place.  This  method  can  be  compared 
to  the  one  sometimes  used  on  land  in  which  the  amount  of  the 
excavation  is  deduced  by  tallying  the  vehicles  that  are  carrying - 
away  the  excavated  debris. 

The  scows  used  in  connection  with  dredging  are  of  several  different 
types  but  chiefly  the  deck  and  dumping  scows.  When  deck  scows 
are  used,  the  hold  of  the  boat  is  correctly  measured  by  the  engineers 
of  the  two  parties  and  the  cubic  content  of  the  scow  is  then  used 
for  measuring  the  material  removed  from  the  bottom.  When 
the  dumping  scows  are  used  for  the  transportation  of  the  debris, 


SOUNDINGS  AND   HYDRAULIC  SURVEYS  17 

the  cubic  content  of  each  compartment  is  accurately  measured  and 
the  solidity  of  the  various  compartments  of  the  scow  taken  as  the 
base  for  estimating  the  amount  of  the  dredged  material.  When 
instead  of  scows,  the  dredge  is  provided  with  hoppers,  the  cubic 
content  of  the  various  hoppers  are  used  for  the  measurement  of 
the  material  excavated  from  the  bottom. 

The  amount  of  the  excavated  materials  deposited  into  the  scows 
to  be  transported  to  the  dumping  place  can  be  also  measured 
from  the  draft  of  the  scow  itself.  There  is  no  doubt  that  more 
material  will  be  deposited  into  the  scow  the  greater  will  be  its 
draft;  by  gauging  the  draft  of  the  scow  when  empty  and  when 
it  contains  a  certain  determined  load  of  100  tons,  for  instance, 
the  difference  of  the  two  drafts  will  indicate  the  content  of  the 
load  and  from  these  two  points  a  scale  can  be  made  for  the  frac- 
tions of  the  load  as  well  as  its  multiples.  From  this  graduated 
gauge  the  content  of  the  scow  can  be  easily  deduced. 

In  the  construction  of  the  new  stone  breakwater  at  Buffalo, 
N.  Y.,  all  the  stones  were  paid  for  by  the  ton,  and  were  transported 
by  means  of  scows,  either  of  the  deck  or  dumping  type.  For  the 
purpose  of  measuring  the  amount  of  material  transported,  each 
vessel  was  provided  with  glass  gauges  and  graduated  rules  by  which 
the  draft  of  the  vessel  was  ascertained.  A  number  of  deck  scows  were 
built  especially  for  the  work  and  exact  measurements  of  these  vessels 
were  made  before  launching.  From  the  data  thus  secured  elaborate 
tables  were  prepared  showing  the  displacement  for  every  -J-J-Q-  of 
a  foot,  calling  the  bottom  zero. 

The  glass  gauges  were  placed  on  the  keel  forward  and  aft,  and 
consisted  mainly  of  a  wrought-iron  standpipe  3  in.  in  diameter, 
into  which  two  brass  cocks  are  screwed.  Between  the  cocks,  which 
are  from  4J  to  7  ft.  apart,  depending  on  the  sizes  of  the  scows,  was 
placed  a  glass  tube  about  1  in.  in  diameter,  the  whole  apparatus 
resembling  a  water  glass  gauge  as  used  on  a  boiler.  A  wooden  rule 
graduated  in  feet,  tenths  and  hundredths  was  attached  alongside 
of  the  glass  tube. 

The  graduations  of  the  rule  corresponded  exactly  with  the  draft 
of  the  vessel.  This  was  usually  accomplished  by  taking  the  mean 
draft  of  the  vessel  fore  and  aft,  and  setting  the  rules  to  correspond 
with  the  water  in  the  gauge.  Absolutely  quiet  water  was  required 
for  this  work,  and  to  facilitate  it  marks  6  in.  apart  were  accurately 
cut  into  the  sides  of  the  vessels  at  each  end.  To  determine  the  load 


1-8  A  TREATISE    ON  DREDGES   AND   DREDGING 

of  a  vessel,  the  mean  readings  of  the  gauges  were  taken  when  the 
vessel  was  light  and  again  when  loaded,  difference  between 
the  light  and  loaded  readings  as  taken  from  tables  gave  the  desired 
information.  Vessels  which  could  not  be  measured  on  the  ways 
or  in  docks  were  measured  on  the  water,  their  draft  being  obtained 
by  hook  gauges. 

To  check  the  calculated  displacement,  the  load  of  a  vessel  was 
actually  weighed  at  frequent  intervals,  by  means  of  a  track  scale, 
located  at  the  contractor's  quarry.  Remarkable  agreements  were 
found  between  the  two. 

In  the  case  of  dump  scows  it  was  not  possible  to  obtain  the 
load  carried  by  displacement,  and  the  value  of  the  gauge  readings 
was,  therefore,  determined  by  actually  weighing  the  material  on 
the  track  scale,  the  readings  of  the  gauge  being  taken  when  the  scow 
was  light,  and  with  frequent  partial  loads  and  when  fully  loaded. 
The  difference  in  feet  and  decimals  of  the  gauge  readings  divided 
into  the  total  load  gave  the  ratio  per  foot.  This  only  applies  to 
full  loads.  Partial  loads,  as  well  as  large  or  small-sized  stone,  affect 
this  ratio  somewhat. 

Increase  and  Shrinkage  of  Material.  There  is  a  great  difference 
in  the  cost  of  dredging  when  the  material  is  measured  in  place  or  in 
scows.  When  the  specification  states  that  the  material  will  be 
measured  in  place,  two  important  items  should  be  considered. 
These  are  the  increasing  of  volume  of  the  removed  materials,  due  to 
the  fact  that  the  soil  removed  from  its  natural  position  increases 
in  volume,  and  such  an  increase  is  by  no  means  a  transcurable  quan- 
tity. The  second  item  is  due  to  the  work  of  the  subcurrents,  which 
tend  to  stir  up  the  material  and  fill  up  again  the  place  of  excava- 
tion. This  is  caused  by  the  leveling  action  of  water,  especially  in 
very  soft  soils,  as  fine  sands  and  muds,  and  as  a  consequence 
necessitates  the  excavation  of  a  larger  amount  of  material,  in 
order  to  obtain  in  a  permanent  way,  the  depth  required  by  the 
improvement. 

It  will  be  almost  impossible  to  foresee  the  amount  of  material 
that  will  fall  back  into  the  excavated  place,  since  this  depends 
upon  two  factors,  namely  the  direction  and  strength  of  the  currents 
and  the  looseness  of  the  material.  It  is  very  difficult  to  tell  how 
far  the  currents  will  affect  the  soil  at  the  bottom  of  the  improve- 
ment, and  to  estimate  even  in  an  approximate  way  the  amount  of 
material  that  will  fall  back.  It  will  be  advisable  for  the  con- 


SOUNDINGS   AND  HYDRAULIC  SURVEYS  19 

tractor  to  make  allowances  for  this  item  and  roughly  estimate  the 
increased  quantity  to  be  excavated,  after  a  careful  examination  of 
the  local  conditions  of  the  improvement.  In  a  general  way  it  can  be 
said  that  this  quantity  is  always  less  than  10  per  cent  of  the  total 
amount  of  the  excavation. 

Better  known  is  the  increase  in  volume  of  the  excavated  material, 
which  has  to  be  transported  to  the  dumping  place  and  for  which 
no  compensation  will  be  given,  hence  the  expenses  of  transportation 
of  this  large  quantity  of  material  should  be  included  in  the  cost 
of  excavation.  Writing  from  the  experience  gained  with  the  United 
States  sea-going  hydraulic  hopper  dredges  Manhattan  and  Atlantic, 
employed  upon  the  Ambrose  Channel  in  New  York  Harbor,  Mr. 
Henry  N.  Babcock  says  that  each  dredge  was  provided  with  two 
almost  equal  saridbins,  both  carrying  together  when  fully  loaded 
about  2300  cu.yds.  But  ordinarily  a  dredge  would  take  in  a  load 
of  2200  cu.yds.,  approximately  1800  yds.  in  place.  Thus  according 
to  the  experience  of  the  U.  S.  Engineers  in  the  Ambrose  Channel 
the  increase  of  volume  was  estimated  at  400  cu.yds.  per  each  load 
of  2220,  or  in  other  words  it  was  noticed  a  difference  of  22  per  cent 
between  the  material  measured  in  place  and  in  the  hoppers  of  the 
dredges.  The  total  amount  of  the  excavation  required  by  the  improve- 
ment of  the  Ambrose  Channel  was  estimated  at  40,000,000  cu.yds. 
measured  in  place.  Thus  it  necessitated  the  transportation  of  nearly 
9,000,000  cu.yds.  without  any  compensation.  A  very  expensive 
item  indeed,  when  it  is  considered  that  the  transportation  of  this 
material  was  effected  by  the  same  steamer  dredges  which  excavated 
the  bottom.  This  meant  they  suspended  operations  and  steamed 
out  to  sea,  making  a  trip  of  nearly  8  miles  from  shore,  to  dump 
their  content  into  deep  waters.  It  took  over  400  of  these  trips 
to  dispose  of  the  increased  volume  of  the  material,  involving  as  a 
consequence  a  very  large  expenditure.  Since  the  increasing  in 
volume  should  be  always  considered  by  contractors  in  preparing 
bids,  especially  when  the  material  will  be  measured  in  place,  it 
will  be  convenient  to  consider  the  increasing  of  volume  at  30  per 
cent  when  there  are  not  more  definite  data. 

Mr.  Robinson,  in  his  article  on  Excavating  and  Dredging  Machin- 
ery in  Engineering  Magazine,  in  regard  to  the  work  of  the  hydraulic 
dredge  J.  Israel  Tark  says:  The  quantity  of  work  done  was  ascer- 
tained by  taking  the  position  of  the  dredge  on  the  first  of  the  month 
and  again  on  the  first  of  the  following  month,  and  measuring  the 


20  A  TREATISE   ON  DREDGES   AND   DREDGING 

distance  of  length  of  ship  channel  completed  in  that  time.  As  the 
cross  section  of  the  cut  was  practically  uniform  and  the  material 
blue  clay,  which  remains  permanently  in  place,  the  work  of  the  dredge 
could  thus  be  arrived  at  with  a  fair  degree  of  accuracy.  The  quantity 
stated  is  increased  to  scow  measurements  to  compare  with  the  other 
dredges  on  the  same  work  which  load  into  scows,  on  the  basis  of 
place  measurement  being  80  per  cent  of  scow  measurement. 


CHAPTER  IV 

EXCAVATION    OF    SUBAQUEOUS    ROCKS.     GENERAL    DISCUSSION. 
EXCAVATION   BY  HAMMERING 

ROCK  is  the  most  difficult  and  expensive  material  to  be  removed 
from  beneath  the  water.  When,  in  carrying  out  the  work  of 
harbor  or  river  improvements  rock  is  encountered,  its  excavation 
involves  two  distinct  operations: 

(a)  The  breaking  of  the  rock  into  small  fragments. 

(b)  The  raising  of  the  d£bris  to  the  surface  and  its  disposal  in 
any    convenient  manner.     This  last  operation  is  accomplished   by 
means  of  any  ordinary  dredge,  while  the  breaking  of  the  rock  into 
small  fragments  is  done  in  two  different  ways,  viz.,  by  hammering 
and  by  blasting. 

The  Method  of  Hammering.  The  breaking  of  the  rock  into 
small  fragments,  by  hammering,  is  accomplished  by  means  of  devices 
which  strike  powerful  blows.  The  blows  are  delivered  by  gravity, 
when  an  extra  heavy  weight  falling  from  a  certain  height  strikes 
the  rock,  as  in  the  Lobnitz  machine;  or  by  steam  or  compressed- 
air  engines,  when  the  rock  is  struck  by  iron  bars  placed  in  contin- 
uation of  the  piston  rod  of  a  vertical  engine,  as  in  the  Scott  & 
Godsir  cutters.  No  matter  which  method  is  used  the  rock  is  reduced 
into  fragments  of  such  size  that  they  can  be  easily  picked  up  by  any 
ordinary  dredge,  and  in  some  cases  though  material  is  pulverized 
in  such  a  way  that  the  finely  divided  particles  can  be  carried  away 
by  the  current. 

The  Method  of  Blasting.  Submerged  rocks  can  also  be  excavated 
by  blasting.  Different  methods  are  used,  depending  upon  the 
magnitude,  depth  and  location  of  the  rock  to  be  removed.  When 
the  rock  is  entirely  submerged  and  must  be  removed  from  an  exten- 
sive area,  but  in  shallow  water,  the.  most  common  method  is  by 
successive  small  blasts  as  in  the  excavation  of  rock  in  the  open  air. 
The  only  difference  being  that  more  powerful  drilling  machines  are 
used  and  they  are  mounted  on  scows  or  stages  of  special  construction. 

21 


22  A  TREATISE   ON  DREDGES   AND   DREDGING 

These  machines  drill  vertical  holes  which  are  charged  and  fired  in 
round  as  soon  as  a  few  holes  have  been  drilled. 

The  rock  to  be  removed  may  form  a  large  reef  extending  to  the 
surface.  This  may  be  located  in  the  way  of  navigable  channels 
and  form  serious  obstacles  to  navigation.  Such  rocks  being 
isolated,  in  the  middle  of  large  bodies  of  water,  and  far  from  impor- 
tant buildings,  are  conveniently  removed  by  a  huge  single  blast. 
Such  a  blast  can  be  prepared  by  honeycombing  the  rock,  by  sinking 
shafts  and  driving  small  radiating  headings  at  different  levels  and 
from  these  drilling  holes  in  all  directions.  These  numerous  holes 
are  charged  with  explosives  and  are  fired  simultaneously.  This 
method  was  used  in  blasting  the  Flood  Rock  at  Hell  Gate,  in  New 
York  Harbor.  Another  method  of  removing  isolated  reefs  consists 
in  building  a  coffer-dam  all  around  the  rock.  Within  the  coffer-dam 
the  rock  is  removed  in  the  usual  way  as  in  land  work  until  the  pit 
has  been  excavated  to  the  required  depth.  Then  lift  holes  are  driven 
all  around  underneath  the  ring  of  rock  supporting  the  coffer-dam. 
The  holes  are  charged  and  fired  simultaneously  and  the  ledges  of 
rock  surrounding  the  pit  together  with  the  coffer-dam  are  the.n 
broken  and  shattered  by  the  explosion  and  reduced  to  small 
fragments  that  can  be  easily  picked  up  by  dredges.  This  method, 
called  "  lift  holes,"  was  used  in  removing  Henderson's  Point  at 
Portsmouth  Navy  Yard,  New  Hampshire. 

The  following  machines  and  methods  have  been  used  to  break 
subaqueous  rock  by  hammering: 

Scott  &  Godsir  Cutter.  This  machine  (see  Fig.  3)  was  designed 
and  built  in  1897  by  Messrs.  R.  M.  Scott  and  A.  Godsir  in  Sidney, 
New  South  Wales,  and  described  by  Mr.  Charles  Graham  Hepburn 
in  the  Transactions  of  the  Inst.  of  C.  E.  This  rock-breaking  machine 
consists  of  a  drilling  tool  connected  directly  to  a  piston,  recipro- 
cating in  a  steam  cylinder  of  considerable  length,  which  is  carried 
on  a  vertical  slide  or  carrier,  capable  of  vertical  adjustment  on  a 
tower  erected  on  a  barge,  pontoon  or  other  floating  structure. 

The  drill  varies  with  the  class  of  work  to  be  done.  For  ordinary 
rock  excavation  the  head  is  formed  of  three  drills  forged  from  a 
steel  bar  6  in.  by  4  in.  in  cross  section.  The  drill  is  secured  to  the 
end  of  the  piston  rod  by  means  of  a  cotter.  The  cylinder  is  14  in. 
in  diameter  and  5  ft.  in  length;  the  piston  rod  is  6  in.  in  diameter 
at  its  top  and  increasing  to  1\  !.n.  in  diameter  at  the  lower  end,  and 
is  guided  by  three  bearings.  To  obviate  the  danger  of  the  piston 


EXCAVATION  OF  SUBAQUEOUS  ROCKS 


23 


striking  the  bottom  of  the  cylinder  with  sufficient  force  to  cause 
injury  to  the  cover,  a  supplementary  steam-pipe  taking  its  supply 
from  the  valve  casing  is  led  into  the  bottom  of  the  cylinder. 
This  arrangement  insures  a  constant  supply  of  steam  at  boiler 
pressure  on  the  lower  side  of  the  piston,  acting  on  it  as  a  brake 
or  buffer  in  its  descent.  The  cylinder  is  securely  bolted  to 
the  carrier.  This  is  formed  of  two  square-edged  vertical  beams 
12x12  in.  and  a  framing  of  12  x  6  in.  timbers  bolted  together  so 
as  to  provide  a  rigid  structure.  The  carrier  slides  vertically 
along  the  faces  of  the  tower  and  has  its  movement^  controlled  by 
a  steam  winch.  The  carrier  is  secured  from  transverse  movement 
on  the  tower  by  a  T-shaped  guide  or  retaining  piece  bolted  to  its 


FIG.  3. — Scott  &  Godsir  Rockcutter. 

vertical  timbers  and  sliding  between  the  two  upright  timbers  of 
the  tower  and  engaging  them  on  their  back.  The  carrier  is  provided 
with  a  shelter  for  the  steam  cylinder  and  the  operator.  Also  the 
tower  consists  of  two  vertical  beams,  each  12  in.  square  in  cross 
section,  set  1  ft.  apart  and  braced  with  diagonal  struts  and  steel  grip 
wires.  The  steam  is  conveyed  from  the  boiler  to  the  cylinder  by 
means  of  a  4-in.  steam  pipe,  trunnioned  at  the  joints  to  permit  of 
vertical  movement.  One  of  the  pipe-lengths  is  guided  by  a  quad- 
rant piece  and  is  reinforced  by  timber  bolted  to  the  pipe,  which 
bears  against  the  quadrant. 

In  regard  to  the  efficiency  of  this  machine,  it  was  found  that 
when  the  moving  parts  weigh  about  3J  tons  and  the  stroke  of  the 
piston  is  about  4  ft.,  making  60  strokes  per  minute  this  apparatus 
will  break  more  than  30  cu.yds.  of  solid  rock  per  day. 


24  A  TREATISE  OX  DREDGES   AND   DREDGING 

Steam  Punch.  In  the  year  1854  Mr.  Charles  T.  Harvey,  the 
designer  and  builder  of  the  first  New  York  elevated  railroad,  while 
engaged  in  the  construction  of  the  St.  Mary's  Falls  ship  canal  was 
compelled  to  remove  a  ledge  of  solid  rock,  over  1000  cu.yds.,  encount- 
tered  on  Lake  Superior,  just  at  the  mouth  of  the  canal.  He  had 
only  a  dredge  of  very  small  capacity,  which  was  of  no  use  for  such 
work.  He  constructed  a  new  machine  which  he  called  a  steam  punch, 
described  by  Mr.  Benjamin  E.  Buchmann,  as  follows: 

The  machine  consisted  of  a  shaft,  which,  dropping,  struck  on 
the  submerged  rock  with  a  force  of  20  tons  per  sq.in. — a  blow  that 
no  rock  could  withstand.  He  used  a  wrought  iron  shaft  16  in.  in 
diameter  and  tapered  down  to  1  in.  square  steel-faced  point.  To 
this  was  welded  a  socket  formed  out  of  the  wrought  iron  fluke  of 
a  propeller's  wheel.  Into  this  socket  was  keyed  the  end  of  a  heavy 
oak  timber  to  form  the  punch  or  chisel,  weighing  altogether  over 
a  ton,  and  striking  a  blow,  as  stated,  of  20  tons  per  sq.in.  By  a 
system  of  gauges  and  stops  it  was  known  whe,n  the  punch  had 
penetrated  below  the  desired  depth,  when  it  was  moved  a  given 
distance  dropped  again,  until  the  submerged  rock  was  broken  into 
such  fragments  as  could  be  readily  removed  by  the  dredge.  The 
required  machinery  was  mounted  on  a  scow.  It  took  6  weeks  to 
break  the  ledge,  which  was  from  1  in.  to  3  ft.  higher  than  the 
required  level. 

Thus  the  method  of  breaking  subaqueous  rock  by  falling  weights 
used  in  the  Lobnitz  machine  was  employed  in  the  United  States 
some  years  ago. 

Lobnitz  Rockcutter.  Messrs.  Lobnitz  &  Co.  of  Renfrew,  Scotland, 
have  constructed  a  very  efficient  rock-cutting  machine  which  has 
been  extensively  used  in  difficult  subaqueous  excavations  all  over 
the  world.  It  was  successfully  employed  in  the  deepening  and 
widening  of  the-  Suez  Canal.  The  Lobnitz  machine  was  illustrated 
in  Engineering  from  which  this  slightly  condensed  description 
was  taken. 

The  machine  (see  Fig.  4)  is  built  on  the  principle  of  a  floating 
pile  driver;  but  the  monkey  of  the  latter  is  replaced  by  a  heavy 
rod  of  steel  armed  at  its  lower  end  with  a  renewable  ogival  head. 
This  steel  ram  or  chisel  may  weigh  complete  from  4  to  20  tons  and 
is  allowed  to  fall  from  a  height  of  6  ft.  to  10  ft.  on  to  the  rocky 
bottom  to  be  excavated.  The  weight  of  the  ram  used  depends  not 
only  on  the  hardness  of  the  rock,  but  also  on  the  depth  of  the  water, 


EXCAVATION  OF  SUBAQUEOUS  ROCKS 


25 


the  rule  adopted  by  the  makers  being  to  make  the  ram  1  ton  in 
weight  for  each  meter  of  depth.  The  whole  force  of  the  impact  is 
concentrated  on  a  few  square  inches  of  rock  surface,  so  that  the 
hardest  rock  is  readily  split  and  pulverized. 

The  ram  falls  through  a  well  in  which  is  a  fixed  hardwood  guide. 
This  guide  is  short  and  loose  fitting,  and  it  therefore  permits  the 
cutter  a  certain  degree  of  freedom  in  an  angular  direction.  The 
guide  is  mounted  so  that  it  can  be  adjusted  vertically  to  suit  different 
depths  of  water  and  is  provided  with  renewable  wearing  plates  and 
spring  cushions  to  deaden  any  shock. 


FIG.  4. — Lobnitz  Rockcutter. 

"The  cutter  bars  are  provided  with  ogival  heads,  having  a  center 
harder  than  their  circumference  and  consequently  are  self-sharpen- 
ing, the  rack  wearing  away  the  hard  center  less  rapidly  than  the 
softer  surrounding  metal.  The  other  end  of  the  ram  is  attached 
to  a  wire  rope  which  is  wound  around  the  drum  of  a  hoisting  engine. 
The  rope  drum  is  loose  on  its  shaft,  being  driven  by  a  friction  clutch, 
which  is  automatically  thrown  into  gear  the  instant  the  ram  reaches 
the  rock.  This  is  effected  by  a  bell  crank  lever  carrying  a  sheave 
which  is  pressed  against  the  lifting  rope  by  a  weight  on  the  short 
arm  of  the  bell  crank.  When  the  ram  reaches  the  rock  the  lifting 
rope  slackens,  and  as  a  consequence,  the  bell  crank  lever  moves 
forward  under  the  influence  of  the  aforementioned  weight,  and  this 


26  A  TREATISE   ON  DREDGES   AND   DREDGING 

movement  is  caused  by  suitable  connections  to  throw  the  friction 
clutch  into  gear. 

To  break  the  rock  the  ram  is  dropped  on  the  same  spot  time 
after  time  till  the  desired  depth  is  reached;  but  if  a  greater  depth 
of  excavation  is  needed  it  is  usual  to  execute  the  excavation  in 
installments,  first  breaking  up  a  layer  3  ft.  to  6  ft.  thick,  this  thickness 
depending  on  the  character  of  the  rock.  The  broken  rock  is  then 
dredged  away,  and  the  work  resumed  on  the  cleaned  surface  till 
the  desired  depth  is  attained.  In  finishing  off,  this  depth  should 
be  about  9  inches  more  than  the  depth  of  the  excavation  so  as  to 
make  certain  that  the  dredge  buckets  on  removing  the  debris  shall 
meet  with  no  obstruction.  It  is  very  important  that  the  ram  should 
fall  exactly  on  the  same  spot  on  repeating  its  blows,  a  movement 
of  even  a  few  inches  reducing  the  efficiency  of  the  machine.  Accurate 
maneuvering  is  thus  very  important,  and  this  is  obtained  by  means 
of  sighting  rods  which  are  collimated  with  base  lines  placed  on  land. 
During  work,  the  man  in  charge  constantly  controls  the  position 
of  the  barge  by  keeping  his  eye  on  the  sight-rods.  After  the  work 
is  finished  in  one  spot  it  is  necessary  to  move  to  a  fresh  one  about 
3  ft.  away.  This  is  done  by  means  of  six  mooring  chains  operated 
with  steam  winding  gear. 

In  practice  it  is  found  that  it  is  best  to  space  the  blows  3  ft. 
apart.  If  wider  spacing  is  adopted  a  greater  quantity  of  rock  is 
loosened,  but  it  is  not  as  completely  broken  up  and  therefore  cannot 
be  dredged  economically.  With  3  ft.  spacing,  approximately  o(X 
per  cent  of  the  whole  mass  is  absolutely  pulverized,  and  the  sand 
thus  formed,  if  there  be  a  strong  current,  is  washed  away.  In  hard 
rock  at  least  2  cu.ft.  are,  on  the  average,  broken  per  blow,  so  that, 
with  a  single-cutter  machine  about  9  cu.yds.  may  be  taken  as  effective 
work.  The  machine  can  be  built  either  with  one  or  with  two  rams. 
The  efficiency  of  the  double-cutter  machine  is  almost  double  that  of 
the  single  one.  To  handle  the  machine  a  crew  of  six  men  is  required 
in  the  case  of  a  single  cutter,  and  eight  for  a  double  cutter.  The 
former  will  consume  1  ton  of  coal  per  ten-hour  day  and  the  latter 
1J  tons. 

Concerning  the  progress  and  cost  of  the  work  of  the  Lobnitz 
machine  Mr.  W.  Henry  Hunter,  chief  engineer  of  the  Manchester 
Ship  Canal,  has  given  the  following  report : 


EXCAVATION  OF  SUBAQUEOUS  ROCKS          27 

• 

MANCHESTER  SHIP  CANAL;    DEEPENING  FROM  26  FT.  TO  28  FT.; 
LOBNITZ  ROCKCUTTER  No.  1. 

Average  quantity  (over  a  period  of  ten  months)  of  rock  broken 

up  per  month 6403  cu.yds. 

Average  cost  of  breaking 8.94d.  per  cu.yd. 

Minimum   quantity  of  rock  broken  per  month 5622  cu.yds. 

Maximum  quantity  of  rock  broken  per  month 10180      ' ' 

The  cutter  has  worked  on  double  shift  regularly,  and  the  average 
cost  of  working  in  this  manner  has  been  £240  per  month,  made  up 
as  follows: 

Wages .' £108 

Coals  and  stores 27 

Repairs  and  renewals,  including  new  ropes  and  repairs  to  needle 105 

£240 

The  rate  of  advance  of  the  rockcutter  averages  36  ft.  per  diem, 
the  bottom  width  of  the  canal  being  120  ft. 

(Signed)  W.  HENRY  HUNTER. 

'ENGINEER'S  OFFICE,  June  19,  1906. 

The  Lobnitz  rockcutter  has  just  been  introduced  in  the  United 
States  by  Mr.  Lindon  W.  Bates,  former  president  of  the  Empire 
Engineering  Corporation  of  New  York  in  the  work  at  Black  Rock 
Harbor  and  the  channel  of  the  Niagara  Ship  Canal.  The  machine 
used  by  Mr.  Bates  was  thus  described  in  the  Engineering  Record, 
.March  16,  1907. 

The  rockcutter  which  is  to  be  employed  in  the  Black  Rock 
Harbor  and  channel  was  especially  designed  for  this  work  by  Mr. 
F.  W.  Allen,  engineer  for  the  Empire  Engineering  Corporation. 
The  hull  is  composite,  being  composed  of  two  separate  hulls,  each 
96  ft.  long  and  17  ft.  beam,  which  are  fastened  together  by  screw 
clamps,  forming  one  hull  96  ft.  long  and  34  ft.  beam  when  in  service. 
The  hull  draws  about  3  ft.  6  in.  of  water  when  fully  loaded,  and 
the  rockcutter  is  ready  for  operation.  The  object  of  building  the 
hull  in  two  parts  is  to  allow  each  hull  to  pass  the  locks  of  the  present 
Erie  Canal,  in  case  the  rockcutter  should  be  dismantled  for  shipment 
to  other  points. 

The  essential  part  of  the  rockcutter,  of  course,  is  the  cutter, 
which  was  made  by  the  Bethlehem  Steel  Co.,  Pennsylvania.  It  is 
a  steel  cylinder,  28  in.  diameter,  about  25  ft.  long  and  weighing 
46,000  Ibs.  It  is  fitted  at  the  lower  end  with  a  hardened  steel  conical- 


28  A  TREATISE  OX  DREDGES   AND   DREDGING 

shaped  point,  resembling  the  end  of  a  projectile.  At  the  upper  end 
there  is  an  eye  to  which  a  steel  cable  is  attached,  leading  from  a 
very  powerful  steam  winch  of  special  design,  built  by  the  Lobnitz 
Co.,  of  Renfrew,  Scotland. 

The  hull  is  maneuvered  by  a  six-drum  steam  Mundy  hoisting 
engine,  by  means  of  six  }-in.  wire  cables,  each  1000  ft.  long.  One 
of  these  leads  forward  from  the  bow,  one  aft  from  the  stern,  and 
one  each  from  the  four  corners  to  port  and  starboard.  The  anchor 
cables  pass  from  the  drums  through  the  deck  sheaves,  and  run  out 
from  the  deck  level  to  the  anchors,  previously  placed  in  position. 
After  the  machine  has  been  placed,  the  steel  cylinder  is  raised  by 
the  hoisting  winch,  and  then  let  fall  onto  the  bed  rock.  This  operation 
is  repeated  until  the  desired  result  is  achieved.  The  hull  is  then 
moved  to  a  new  position  by  taking  in  the  cables  on  one  side  and 
paying  them  out  on  the  opposite  one,  after  which  the  rock  crusher 
is  raised  and  let  fall,  and  so  on. 

Steam  is  furnished  by  a  large  locomotive  boiler.  The  machine 
is  also  supplied  with  an  electric  plant  and  searchlight  for  night  work. 

The  contract  price  for  removing  the  bed  of  rock  on  this  work 
is  $1.85  per  cu.yd.  measured  in  place. 

An  American  company  has  lately  been  organized  to  manufacture 
and  sell  rockcutters  of  the  Lobnitz  pattern. 

There  is  also  now  being  used  in  this  country  a  rockbreaker  or 
cutter  that  instead  of  the  hammer  falling  in  a  shaft  by  gravity,  it 
operates  in  a  compressed  air  cylinder.  It  is  claimed  that  a  more 
powerful  blow  is  struck  in  this  manner  and  the  blow  is  controlled. 
Except  for  air  being  used  the  principle  is  similar  to  the  Scott  & 
Godsir  cutter, 


CHAPTER  V 

EXCAVATION     OF     SUBAQUEOUS     ROCKS— BY   BLASTING- 
COMPARISON   OF   THE   TWO   METHODS 

SUBMERGED  rock  can  be  removed  by  small  successive  blasts 
fired  in  rounds  as  quickly  as  the  holes  are  drilled  and  charged. 
Such  a  method  is  used  in  the  excavation  of  submerged  rock  encoun- 
tered at  a  comparatively  shallow  depth  and  for  some  years  has  been 
the  most  common  method  of  removing  subaqueous  rock.  Blasting 
rock  in  connection  with  dredging  was  done  in  England  years  ago. 
The  Encyclopedia  Brittanica  mentions  the  works  of  Rennie  at  Newry 
and  Stevensons  at  Ballyshannon  as  executed  in  this  manner.  The 
same  method  was  afterward  extensively  used  by  Mr.  William  Cubitt 
on  the  Severn.  It  was  described  by  Mr.  Evans  in  the  Proc.  Inst. 
of  C.  E.,  Vol.  IV,  and  condensed  as  follows: 

Drilling  Plants.  In  removing  marl  beds  along  the  channel  of 
the  Severn,  after  the  dredges  had  been  unsuccessfully  employed, 
new  methods  were  tried,  one  of  them  consisting  in  scraping  the 
bottom  of  the  channel  with  a  plow,  another  to  drive  into  the 
hard  soil  iron  rods,  so  as  to  loosen  the  material.  However,  it  was 
decided  that  the  only  possible  way  was  to  recourse  to  blasting. 
For  this  purpose,  from  a  raft  moored  into  the  river  were  lowered 
iron  pipes  3J  in.  in  diameter  and  sunk  well  into  the  marl.  Through 
these  pipe  holes  were  bored  first  with  a  IJ-in.  jumper  and  then 
with  an  auger.  The  holes  were  bored  6  ft.  apart  each_  way.  The 
cartridges  were  formed  in  the  ordinary  way  with  canvas  and  fired 
with  Blickford  fuses. 

In  breaking  rock  by  blasting  on  the  Rhine  River,  between  Bingen 
and  Coblenz,  in  the  year  1863,  Mr.  Hipp  successfully  employed 
a  new  device  for  drilling  holes,  which  has  been  in  constant  service 
until  very  recently.  This  consists  of  a  drilling  machine  in  which  the 
drill  5  meters  long  was  fastened  to  the  axis  of  the  piston.  It  was 
raised  by  steam  power  and  let  fall  by  its  own  weight.  The  weight 
of  the  rod  was  from  150  to  200  kg.  and  the  machine  was  able  to 

29 


30  A  TREATISE  ON  DREDGES   AND   DREDGING 

strike  from  110  to  130  blows  per  minute.  It  took  from  10  to  15 
minutes  to  sink  holes  8  cm.  in  diameter  to  the  depth  of  .05  to  .1  m. 
With  these  machines  from  8  to  10  holes  from  1  to  1 . 80  m.  deep  were 
made  in  a  day. 

In  this  country,  in  the  year  1866-67  Mr.  Dunbar  used  a  method 
of  his  own  for  blasting  a  rock  bed  from  the  channel  and  harbor 
of  Erie,  Pa.,  on  Lake  Erie.  It  was  described  by  Mr.  Dean  in  the 
Proceedings  of  the  Am.  Soc.  of  C.  E.;  the  ledge  of  rock  excavated 
was  only  6  ft.  deep.  It  was  drilled  by  hand  by  means  of  jumpers 
or  crowbars,  the  men  standing  on  the  ice  in  winter  and  on  a  specially 
constructed  raft  in  other  seasons.  The  thickness  of  the  ice  guided 
the  drills  to  strike  their  blows  in  the  same  spot.  The  raft  was  rigged 
with  a  device  so  as  to  make  the  drills  repeat  their  blows  in  the  same 
place. 

This  rough  device  led  to  the  design  of  the  modern  drilling  machine. 
In  the  year  1872  Mr.  Dunbar  undertook  the  excavation  of  a  sub- 
merged rock  at  Port  Colborne,  Lake  Erie,  and  the  drilling  was  done 
by  hand.  The  rock,  however,  was  so  hard  that  three  men  could 
hardly  drill  1  ft.  per  day.  Accordingly  Mr.  Dunbar  constructed  a 
drilling  machine,  using  the  hull  of  an  old  dredge  to  carry  the  machin- 
ery. The  scow  was  provided  with  vertical  spuds  at  each  corner  to 
hold  it  firmly  in  position.  A  track  was  laid  on  the  edge  of  the  deck 
on  which  the  drills  were  moved.  On  this  track  were  mounted  two  5 
in.  steam-cylinder  percussion  drills,  arranged  to  slide  up  and  down 
in  a  vertical  frame  overhanging  the  side  of  the  scow.  The  drills 
were  raised  or  lowered  by  means  of  a  windlass  operated  by  hand, 
and  were  moved  along  the  track  by  means  of  crowbars.  The  scow 
was  50  ft.  long,  and  by  starting  one  drill  at  the  end,  and  the  other 
at  the  middle  of  the  track,  each  drilling  five  holes  at  intervals  of 
5  ft.,  it  was  possible  to  drill  ten  holes  from  one  position  of  the  scow. 
Holes  9  ft.  deep  could  be  drilled  without  changing  the  drill  bits  for 
longer  ones.  As  soon  as  a  hole  was  drilled  to  the  requisite  depth, 
it  was  charged  and  blasted  without  moving  the  scow.  When  one 
row  of  holes  had  thus  been  disposed  of,  the  scow  was  moved  back 
from  the  face  of  the  excavation  a  distance  of  6  ft.  and  the  operation 
was  repeated. 

This  method  of  drilling  holes  was  afterward  greatly  improved. 
A  hydraulic  ram  was  introduced  in  order  to  move  the  drills  both 
vertically  and  horizontally.  The  great  inconvenience  arising  from 
the  debris  which  filled  the  bottom  of  the  hole,  thus  forming  a  cushion 


EXCAVATION  OF  SUBAQUEOUS  ROCKS 


31 


and  preventing  the  bit  from  striking  the  rock  in  *the  successive 
blows,  was  obviated  by  the  introduction  of  a  pump  which  forced 
a  jet  of  water  into  the  drill  holes  for  the  purpose  of  cleaning  them 
of  debris. 

Fig.  5  shows  a  modern  plant  for  subaqueous  drilling  designed 
and  used  by  Mr.  William  L.  Saunders  for  the  removal  of  rock  in 
New  York  Harbor.  It  consists  of  an  old  scow  or  hulk,  upon  which 
are  housed  the  boiler  room,  the  engine  room  and  the  blacksmith 
shop,  and  a  detached  drill  stage,  which  is,  however,  connected  to  the 


FIG.  5. — Saunder's  Machine  for  Subaqueous  Rock  Excavation. 

boat  by  a  gangplank.  The  drill  stage  chiefly  consists  of  a  wooden 
platform  supported  by  four  adjustable  legs  sliding  into  castings, 
so  that  they  may  be  adjusted  to  any  height  and  regulated  according 
to  the  tides,  so  as  to  have  the  platform  always  above  the  water- 
level.  The  platform  or  stage  is  provided  with  slots  cut  both  in 
the  longitudinal  and  transverse  direction  in  order  to  allow  the  points 
of  the  drills  to  go  through.  Located  on  the  stages  are  two  drilling 
machines  of  the  automatic-feed  type  mounted  on  tripods.  They  are 
provided  with  an  extension  piece  operating  through  a  submarine 
tube,  which  extends  underneath  the  platform,  and  is  used  to  direct 
the  blows  of  the  drills.  These  drill  stages  will  stand  heavy  blasting. 


32 


A  TREATISE  ON  DREDGES   AND   DREDGING 


This  was  proven  at  New  York,  where  at  times  hundreds  of  pounds 
of  dynamite  were  blasted  under  the  platform  without  injuring  it. 
In  blasting  rock  at  the  Iron  Gates  on  the  River  Danube  a  different 
device  was  used,  shown  in  Fig.  6.  This  consists  of  a  floating 
rectangular  platform  provided  with  four  spuds  of  large  dimensions 
which  can  be  raised  and  lowered  by  means  of  chains,  each  com- 
manded by  a  windlass.  In  this  way  the  platform  can  be  either  made 
to  float  so  as  to  be  easily  transported  from  one  point  to  another,  or 
firmly  fixed  to  the  bottom.  A  very  long  pit  provided  with  tracks 
on  the  edge  of  the  longitudinal  sides  is  located  in  the  center  of  the 


FIG.  6. — Drilling  Platform  used  on  the  Danube  River. 

platform.  A  platform  with  boiler  and  engines  and  carrying  four 
drills  of  the  rotary  type  is  mounted  on  a  truck  running  along  the 
tracks.  The  drills  are  mounted  5  ft.  apart  and  by  moving  the  truck 
from  one  end  to  another  of  the  long  pit,  many  rows  of  drill  holes  can 
be  bored.  After  all  the  holes  have  been  charged  the  spuds  are  raised 
and  the  float  moved  50  or  60  yds.  away,  to  return  and  resume  work 
after  blasting  all  the  holes,  by  means  of  wires  attached  to  an 
electric  machine  located  on  board  the  float. 

For  blasting  subaqueous  rocks  there  are  other  drilling  machines 
in  which  the  drills  instead  of  working  through  pits  in  the  middle  of 
the  float,  are  located  at  the  edges  of  the  boat.  These  machines  may 


EXCAVATION  OF  SUBAQUEOUS  ROCKS 


33 


be  provided  either  with  one  or  several  drills.  Fig.  7*  shows  a  single 
drilling  machine  as  built  by  the  Ingersoll-Sergeant  Co.  This  consists 
of  an  ordinary  scow  or  pontoon  supporting  a  wooden  frame  similar 
to  the  one  used  in  connection  with  a  pile-driving  machine,  and 
erected  on  the  front  edge  of  the  pontoon.  A  drill  of  large  size  is 
mounted  on  these  leads.  The  leads  can  be  made  of  any  desired 
length  and  are  equipped  with  a  hand  and  power  feed,  used  for  raising 
the  drill  in  the  leads  or  guide.  An  automatic  lead  is  provided  for 
feeding  the  drill  down  as  it  cuts  away  the  rock.  The  drill  and  feeding 
arrangements  are  fastened  to  a  spud  which  is  placed  between  wooden 


FIG.  7. — Ingersoll  Drilling  Scow.        , 

or  iron  guides  for  the  purpose  of  raising  or  lowering  the  apparatus 
to  suit  the  various  depths  of  water.  The  drilling  is  done  through  a 
tube  which  rests  on  the  rock  and  supports  the  weight  of  the  spud 
carrying  the  drill.  The  drill  steel  is  hollow  and  has  a  valve  placed 
in  it  near  the  bottom,  which  acts  the  same  as  a  pump,  the  cut- 
tings being  forced  up  and  out  at  the  top.  The  drill  is  operated 
from  a  boiler  located  on  the  deck  of  the  scow. 

To  blast  large  quantities  of  rock  in  a  comparatively  short  time, 
more  powerful  machines  are  employed.  These  consist  of  scows 
carrying  a  whole  battery  of  drills,  together  with  their  equipment. 
In  such  a  case  the  boiler  must  be  proportionate  to  the  work  required 


34 


A  TREATISE    OX   DREDGES   AND   DREDGING 


by  a  larger  number  of  drills.  These  machines  are  similar  to 
those  described  above,  the  only  difference  being  that  three  or 
four  drills  are  mounted  either  on  the  port  or  starboard  sides  of  the 
pontoon  and  their  distance  apart  being  equal  to  the  required  dis- 
tance of  the  drill  holes.  Fig.  8  shows  one  of  these  machines  as  built 
by  the  Rand  Drill  Company. 

A  uniform  bottom  cannot  be  obtained  by  blasting  the  rock  in 
the  manner  just  described,  on  account  of  irregular  ruptures  caused 
by  lack  of  uniformity  in  the  quality  of  stone.  When  it  is  desired 
to  have  a  level  bottom  the  drilling  must  be  made  from  a  shaft  or 


FIG.  8. — Rand  Drilling  Boat. 

caisson.  The  shaft  can  be  constructed  of  different  materials,  but 
it  is  more  convenient  to  build  it  in  the  shape  of  a  metallic  caisson 
suspended  from  a  boat,  or  better,  between  two  boats  close  together 
with  a  space  for  the  caisson  between  them.  After  the  boat  or  boats 
have  been  anchored  and  made  firm  to  the  bottom  the  caisson  is  let 
clown  to.  the  bed  of  the  river  and  the  water  forced  out  by  means 
of  compressed  air,  which  is  also  used  for  operating  the  drills.  The 
holes  are  drilled  about  a  yard  below  the  desired  level  of  the  bottom. 
After  the  dynamite  cartridges  have  been  put  in  place  the  boat  is 
pushed  off  to  one  side  for  a  distance  of  about  130  to  160  ft.,  all  the 
cartridges  being  exploded  simultaneously  by  electricity;  then  the 


EXCAVATION  OF  SUBAQUEOUS  ROCKS          35 

boat  is  brought  back  into  position  for  blasting  and  the  shaft  is  sunk 
again.  The  loosened  rock  can  be  removed  either  through  the  shaft, 
which  is  a  comparatively  slow  operation,  or  can  be  removed  later 
by  means  of  dredges.  The  principal  advantages  of  such  a  shaft 
consist  in  the  facility  thus  offered  for  examining  every  part  of  the 
bottom  and  leveling  it  by  hand  where  necessary  and  in  the  ease  with 
which  the  seat  of  operations  can  be  changed  without  loss  of  time. 

The  boat  shown  in  Fig.  9  with  a  central  opening  for  the  metallic 
caisson  was  found  very  convenient  in  blasting  rocks  on  the  Rhine 
River  where  the  machinery  had  to  be  moved  frequently  to  make 
room  for  the  passage  of  floats  and  tows  made  up  of  a  number  of 
boats.  Each  of  the  shafts  employed  there  covered  a  surface  of 
about  27.5  sq.yds.  in  which  as  a  rule,  fourteen  to  seventeen  holes 
were  drilled.  The  blasting  operations  extended  over  a  surface  of  49 
sq.yds.,  so  there  was  one  hole  for  about  2.7  sq.yds.  of  blasting 
surface.  On  an  average  360  ft.  of  hole  was  drilled  per  day  by 
one  shaft.  During  the  operations  in  the  Rhine,  near  Bingen,  about 
260,000  cu.yds.  of  stone  were  blasted  out. 

A  similar  device  is  also  used  in  California  in  connection  with 
gold  mining.  There  the  river  beds  carry  much  fine  gold,  and  by 
dropping  a  small  caisson  from  the  center  of  the  boat  men  are  able 
to  go  to  the  river  bottom,  excavate  the  gold-bearing  sand  and  gravel 
and  by  means  of  hoisting  machinery  elevate  it  to  the  separators 
on  board  the  scow.  Such  caissons  are  much  smaller  than  those 
used  for  rock  drilling.  The  use  of  such  caissons,  however,  has  not 
been  extensive,  and  their  value  is  disputed  among  mining  engineers. 

Excavation  of  subaqueous  rocks  can  be  done  in  some  cases 
without  any  previous  drilling,  by  simply  placing  dynamite  cartridges 
on  the  ledge  of  rock  at  the  bottom  of  the  river.  In  such  cases  the 
rock  is  broken  into  slabs  and  the  fragments  are  carried  away  by  the 
current  or  are  raised  by  dredges.  It  is  obvious  that  with  this  method 
of  blasting  subaqueous  rocks,  a  larger  quantity  of  dynamite  should 
be  used  than  with  the  usual  manner  of  blasting  by  drilling  holes 
to  receive  the  charge.  Consequently  it  is  seldom  used  except  when 
a  small  quantity  of  rock  must  be  removed  and  the  ledge  is  thin. 

Blasting.  After  the  holes  have  been  drilled  by  means  of  any  one 
of  the  numerous  devices  already  described,  they  are  charged  with 
explosives.  There  are  several  methods  of  charging  drill  holes,  but 
the  one  most  commonly  used  was  devised  by  Mr.  Dunbar,  the  pioneer 
of  subaqueous  drilling.  Mr.  Dunbar's  apparatus  consists  of  a  cop- 


I 


EXCAVATION  OF  SUBAQUEOUS  ROCKS          37 

per  cylinder  of  smaller  diameter  than  the  drill  hole  but  of  sufficient 
length  to  admit  the  entire  cartridge.  At  the  upper  end  is  attached 
a  piece  of  iron  gas  pipe  long  enough  to.  extend  well  above  the  surface 
of  the  water.  The  copper  cylinder  is  slotted  on  one  side  through- 
out its  length  to  permit  the  insertion  of  the  cartridge,  with  its 
exploding  wires  fastened  to  the  upper  end.  When 'the  cartridge 
with  its  wires  has  been  passed  in.to  the  cylinder,  the  latter  is  inserted 
in  the  drill  hole,  and  a  long  pole  is  passed  down  through  the  gas 
pipe  forming  the  extension  of  the  cylinder.  The  whole  pipe  is 
then  withdrawn,  the  pole  being  used  to  prevent  ihe  cartridge  from 
coming  with  the  cylinder.  As  soon  as  the  charging  apparatus  has 
been  entirely  removed,  the  cartridge  is  exploded. 

Costs.  Concerning  the  cost  of  excavation  of  rock  under  water 
by  blasting,  Mr.  T.  Jenkins  Hains,  while  in  charge  of  the  New 
York  office  of  the  Nicaragua  Canal  Commission,  collected  valuable 
data  from  the  report  of  the  Chief  Engineer  of  the  U.  S.  Army  con- 
cerning the  cost  of  dredging  rock  in  the  year  1897,  in  different  parts  of 
the  country.  He  gives  the  following  examples  of  the  cost  of  rock 
excavation  under  water: 

Cocheco  River,  N.  H ledge  1300  cu.yds.       7  ft.  deep     $7.50  cu.yd 

Bronx  River,  N.  Y , 


Sullivan  Falls 

Kennebec  River 

Sassanoa  River.  .  .  . 

Moosabu,  Me 

Boston  Harbor. . 


1300  6 

not  stated         10 
1300  cu.yds.     10 


800      "         not  stated        10.48 


800 

8772      "  27 


6.89 
16.48 

9.87 


13.75 
16.48 


From  these  examples  it  can  be  deduced  that,  broadly  speaking, 
the  cost  of  rock  excavation  under  water  is  directly  proportional  to 
the  depth  of  the  ledge  and  inversely  proportional  to  the  quantity. 
But  a  more  correct  idea  of  the  cost  of  removing  subaqueous  rocks 
by  blasting  and  dredging  can  be  obtained  from  the  following  examples 
taken  from  Engineering  News,  Vol.  LVI.  These  show  the  results 
obtained  by  two  different  contractors  in  removing  ledges  of  calcare- 
ous rocks,  in  deepening  the  channel  of  the  Detroit  River,  the  con- 
tractors working  on  two  different  sections. 

The  contractors  for  Section  2,  Messrs.  G.  H.  Breymann  & 
Bro.  of  Toledo,  O.,  agreed  to  excavate  the  rock  at  the  following 
prices:  $3.25  per  cu.yd.  bank  measurement,  for  all  the  material 
above  the  22-ft.  grade,  and  $1.625  per  cu.yd.  for  all  material  removed 
between  the  22-  and  24-ft.  grades.  The  contractor's  plant  consisted 


38  A  TREATISE  ON  DREDGES   AND   DREDGING 

of  2  dredges,  2  drill  boats,  one  with  4  drills  and  the  other  with  2 
drills;  1  derrick  scow  with  diving  outfit,  2  tugs  and  the  necessary 
dump  scows.'  Over  an  area  of  about  39,000  sq.yds.  the  material 
was  broken  up  by  drilling  and  blasting.  The  holes  were  generally 
drilled  at  the  corners  of  5-ft.  squares.  The  number  of  holes  drilled 
was  17,212,  these  being  165,011  lin.ft.,  showing  an  average  depth 
of  9.6  ft.  per  hole.  There  were  removed  from  an  area  of  23,000  sq. 
yds.  33,226  cu.yds.  of  material,  making  an  average  depth  of  4.2  ft. 
This  demonstrates  that  the  holes  must  be  drilled  to  a  depth  over 
twice  that  of  the  material  to  be  removed.  The  total  hours  worked 
by  the  drill  boats  for  all  drills  was  18,358.  This  is  at  the  rate  of  9  ft. 
per  hour — a  remarkably  good  showing.  Of  the  33,226  cu.yds.  of 
material  removed  13,003  cu.yds.  were  of  full-rate  material,  being 
above  the  22-ft.  grade;  17,578  cu.yds.  of  half -rate  material,  being 
between  22-  and  24-ft.  grades,  and  2645  cu.yds.  of  material  for  which 
no  payment  was  made,  being  below  the  24-ft.  grade. 

The  work  on  Section  4  was  performed  by  Mr.  M.  Sullivan  of 
Detroit,  Mich.,  at  the  contract  prices  of  $2.40  per  cu.yd.  bank 
measurement,  for  material  above  the  22-ft.  grade,  and  $1.20  per 
cu.yd.  for  material  between '22-  and  24-ft.  grades.  The  contractor's 
plant  was  composed  of  4  dredges,  4  drill  boats,  two  with  2  drills 
and  two  with  3  drills;  1  derrick  scow  with  diving  outfit,  3  tugs 
and  the  necessary  dump  scows.  Over  an  area  of  about  120,000 
sq.yds.  the  material  was  broken  up  by  drilling  and  blasting./  The 
number  of  holes  drilled  was  36,479,  there  being  260,313  lin.ft.,  show- 
ing an  average  depth  of  7.1  ft.  per  hole.  There  were  used  328,444 
Ibs.  of  dynamite,  or  9  Ibs.  per  hole,  a  little  over  1 J  Ibs.  for  each  foot 
hole.  There  were  removed  from  an  area  of  225,000  sq.yds.  222,635 
cu.yds.  of  material,  which  would  give  an  average  depth  of  nearly 
3  ft.  The  holes  in  this  case  also  were  over  twice  the  depth  of  the 
removed  material.  The  total  hours  worked  by  the  drill  boats  for 
all  drills  was  34,729.  This  is  at  the  rate  of  7.5  ft.  per  hour,  or  consider- 
ably less  than  on  Section  2.  Of  the  222,635  cu.yds.  of  rock  excavated 
78,260  cu.yds.  were  of  full-rate  material,  being  above  22-ft.  grade; 
100,893  cu.yds.  of  half  rate  material,  being  between  22-  and  24-ft. 
grades,  and  for  43,682  cu.yds.  no  payment  was  made,  being  below 
the  24-ft.  grade. 

Of  the  total  amount  of  the  rock  excavated  the  following  shows 
the  percentage  of  work  done  as  compared  with  the  compensa- 
tion: 


EXCAVATION  OF  SUBAQUEOUS  ROCKS          39 


Section  2         Section  4 


Full  rate 39% 

Half  rate 53  45 

Not  paid.. 8  20 

It  would  seem  from  this  that  some  other  plan  or  method  might 
have  greatly  reduced  the  amount  of  work  done  for  half  pay  or  for 
which  no  compensation  was  made,  but  it  is  difficult  to  decide  upon 
this  without  experimenting. 

COMPARISON    OF    THE    TWO    METHODS. 

A  comparative  test  of  the  two  methods  of  breaking  subaqueous 
rocks  was  made  at  Blyth,  England,  and  reported  upon  by  Mr.  John 
Watt  Sandeman  in  Engineering,  June  28,  1907. 

In  the  improvement  proposed  at  Blyth  it  is  necessary  to  remove 
500,000  cu.yds.  of  sandstone  rock  and  shale,  and  the  work  is  now 
being  done  by  means  of  2  Lobnitz  rockbreakers  and  2  700-ton 
hopper  dredges  (of  the  clamshell  type).  Previous  to  1906  about 
150,000  cu.yds.  of  rock  were  broken  up  by  means  of  drilling  and 
blasting,  so  that  a  comparison  of  the  two  methods  can  be  made. 

The  rock  at  Blyth  is  the  sandstone  of  the  Coal  Measures,  vary- 
ing in  character  from  friable  stone  containing  fire  clay,  shale  and 
coal,  to  sandstone  equal  in  hardness  to  basalt. 

Rock  Drilling  and  Blasting.  The  drilling  and  blasting  of  the 
rock  was  carried  out  by  means  of  a  barge  having  6  drills,  which 
were  lifted  by  steam  power  and  guided  by  hand. 

The  distance  between  the  shot  holes  was  5  ft.  in  one  direction 
and  6  ft.  2  in.  in  the  other.  The  blasting  material,  bellite,  was 
lowered  in  canisters  through  the  drilling  tubes,  and  fired  by  fuses 
and  detonators,  the  holes  being  tamped  with  small  gravel. 

The  average  quantity  of  rock  drilled  and  blasted  per  week  by 
means  of  one  barge  was  488  cu.yds.,  and  the  average  cost  of  drilling 
vand  blasting  was  about  3s.  per  cu.yd. 

The  quantity  of  rock  blasted  was  ascertained  by  the  number 
of  holes  and  their  depth,  which  was  1  ft.  more  than  that  to  which 
the  rock  could  be  dredged,  and  a  check  was  made  by  sounding 
over  an  area  of  rock  before  blasting  and  after  dredging. 

Rockbreaking.  Each  rockbreaker  employed  at  Blyth  consists  of  a 
steel  barge  carrying  shear-legs,  from  which  is  suspended  a  steel  ram  of 
15  tons  weight,  40  ft.  to  50  ft.  in  length,  and  17  in.  to  19  in.  in 
diameter,  having  a  renewable  conical  point,  tempered  so  as  to 


40  A  TREATISE  ON  DREDGES   AND   DREDGING 

combine  a  hard  center  with  a  softer  exterior,  which,  while  wearing, 
enables  a  sharp  point  to  be  preserved. 

The  ram  is  lifted  by  a  wire  rope  wound  upon  a  loose  drum, 
driven  by  a  friction-clutch.  It  is  allowed  to  fall  from  a  height  of 
8  ft.,  and  on  an  average  of  eight  to  nine  blows  penetrates  the  rock 
to  a  depth  of  3  ft.  which  is  sufficient  to  allow  of  its  being  dredged 
to  a  depth  of  2  ft.  6  in.  The  machine  is  arranged  so  that  it  can  be 
moved  on  end  and  athwart  simultaneously  by  chains  worked  by 
steam  winches.  By  means  of  sighting  rods  on  board  and  ashore 
the  barge  can  be  moved  over  uniform  distances.  The  ram  was  at 
first  worked  in  positions  3  ft.  apart  and  this  distance  was  gradually 
increased  to  4  ft.  6  in.,  which  was  found  to  be  close  enough  for  either 
hard  or  soft  rock. 

The  average  quantity  of  rock  which  one  machine  has  broken 
is  per  week,  working  night  and  day,  and  allowing  for  all  stoppages, 
908  cu.yds.  at  a  cost  of  S.Sd.  per  cu.yd.  This  is  based  on  six  months' 
working;  but  as  it  is  necessary  to  allow  for  renewal  of  rams,  the 
following  is  the  actual  cost  per  week  of  wages,  coal  stores  and  water, 
and  the  estimated  cost  of  repairs,  full  allowance  being  made  for 
renewal  of  rams  and  all  contingencies: 

£  s       d 

Wages 16  1       6 

Coal,  stores,  and  water 6  10       7 

Estimated  cost  of  repairs,  renewal  of  rams,  ropes,  etc  .22  00 

Insurance  at  30s.  per  cent  =  £102   per  annum 1  19       2 

908  cu.yds.  at  12.3d 46       11       3 

The  cost  of  one  rockbreaker  is  about  £6800  and  if  4  per  cent  be 
allowed  for  interest  and  2J  per  cent  for  depreciation  (the  machine 
being  well  maintained)  the  additional  cost  per  cubic  yard  would 
be  2.2d.  making  a  total  cost  of  about  14. 5d  per  cu.yd. 

The  quantity  of  rock  broken  is  ascertained  by  the  number  and 
depths  of  the  penetrations  of  the  ram  in  a  given  time,  which  are 
carefully  recorded  and  after  dredging  the  amount  of  rock  removed  is 
checked  by  soundings. 

Rock  Dredging.  Each  of  the  hopper  dredges  has  .two  sets  of 
buckets,  one  for  rock  dredging  and  the  other  for  sand,  clay  or  gravel, 
having  50  per  cent  greater  capacity.  The  bucket  lips  are  of  cast- 
steel  and  the  pins  and  bushes  of  manganese  steel.  The  lips  of  the 
buckets  for  rock  dredging  are  set  at  an  angle  of  about  27  degrees 


EXCAVATION  OF  SUBAQUEOUS  ROCKS          41 

to  the  bucket-backs,  and  those  for  sand,  etc.,  at  an  angle  of  55 
degrees. 

Rock  picks  were  tried  between  the  buckets  of  one  of  the  stationary 
dredges,  but  as  they  did  not  assist  in  removing  rock  they  were  not 
employed  in  the  hopper  dredges.  When  in  rock  the  dredges  advance 
by  6-ffc.  lengths,  and  dredge  athwart  for  breadths  up  to  200  ft. 
The  rock  is  loaded  into  hoppers  and  deposited  at  sea,  or  (when 
required  for  harbor  purposes)  into  separate  barges  having  grilled 
hoppers,  enabling  the  rock  to  be  screened  and  discharged. 

In  estimating  the  quantity  of  rock  carried  in  the  hoppers  of  the 
dredges  deduction  has  been  made  for  water  contained  along  with 
the  rock. 

As  compared  with  blasting,  the  rockbreaker  disintegrates  and 
breaks  the  rock  into  smaller  pieces,  so  that  the  quantity  lifted  by 
the  dredges  in  a  given  time  is  about  15  per  cent  more  than  that 
of  blasted  rock. 

The  average  quantity  of  blasted  rock  removed  by  one  dredge 
per  day  of  24  hours,  and  allowing  for  all  stoppages,  is  158  cu.yds., 
and  of  that  broken  by  the  rockbreaker  182  cu.yds.  The  average 
number  of  days  per  annum  worked  by  the  dredges  is  227.  The  cost 
per  cu.yd.  for  dredging  blasted  rock  is  2s.  6d.  The  cost  per  cu.yd. 
of  dredging  rock  broken  by  rockcutter  is  2s.  2d. 

Allowing  4  per  cent  for  interest,  and  2J  per  cent  for  depreciation 
on  £19,000,  the  cost  of  a  dredge,  the  additional  cost  per  cu.yd.  would 
be  8.2d.  for  blasted  rock  and  7. Id.  for  rock  broken  by  rockbreaker. 

Comparative  Costs.  The  comparative  cost  of  rock  removal 
under  the  two  systems  is  as  follows : 

PER  CU.YD. 
s.       d. 

Drilling  and  blasting  rock 3         0 

Dredging  same,  2s.  6d.  +  8.2d 3         2.2 

6         2.2 

Breaking  rock  by  rockbreaker 1         2.5 

Dredging  same,  2s.  2d.  +  7.1d 2         9.1 

3       11.6 

Difference  in  cost  per  cu.yd.  in  favor  of  the  removal  of  rock  by 
means  of  rockbreaker  is  2s.  2.6d. 


CHAPTER  VI 
EXCAVATION  OF  SUBAQUEOUS  ROCKS— BY  A  LARGE  BLAST 

THE  removal  of  subaqueous  rocks  by  a  single  huge  blast  can  be 
accomplished  in  two  different  ways — either  by  honeycombing  the 
whole  reef  and  firing  the  charges  simultaneously,  or  by  a  coffer- 
dam and  series  of  lift  holes. 

Mining  or  Honeycombing  the  Reef.  This  method  was  employed 
by  Gen.  Newton  in  blasting  the  Flood  Rock  at  Hell  Gate,  in  New 
York  Harbor,  and  was  described  by  1st  Lieut.  George  Mc.C. 
Derby,  Corps  of  Engineers,  U.  S.  A.,  in  the  Sanitary  Engineer, 
December,  1885.  The  following  description  is  slightly  condensed 
from  his  paper: 

All  the  vessels  plying  between  New  York  and  Long  Island  Sound 
go  through  Hell  Gate,  a  narrow  and  crooked  waterway  between 
the  rocks,  where  the  East  River  makes  its  way  between  Black- 
well's  Island  and  Ward's  Island.  Since  the  year  1848  it  was  estimated 
that  one  vessel  in  every  fifty  attempting  the  passage  was  more  or 
less  damaged  by  being  thrown  on  the  rocks.  The  channel  was  so 
dammed  by  these  obstructions,  as  to  show  a  difference  of  level 
of  1.9  ft.  at  high  water,  causing  currents  of  8J  knots  an  hour.  The 
necessity  of  removing  these  obstructions  was  felt  for  many  years, 
and  Congress  appropriated  money  at  different  times.  Such  sums, 
however, were  inadequate  for  the  purpose.  When  Gen.  John  Newton, 
Corps  of  Engineers,  U.  S.  A.,  was  placed  in  charge  of  this  improve- 
ment, he  vigorously  presented  the  real  solution  of  the  problem.  Gen. 
Newton  proposed  to  remove  all  the  dangerous  reefs  to  a  depth  of 
26  ft.  at  mean  low  water  and  submitted  detailed  estimates  of  the 
cost  of  the  work  and  the  time  required  to  complete  it.  This  project, 
on  account  of  its  magnitude,  was  first  only  partially  approved,  but 
after  the  successful  demolition  at  Hallett's  Point,  Astoria,  L.  L,  it 
was  adopted  in  its  entirety. 

The  method  adopted  by  Gen.  Newton  at  Flood  Rock  was  as 
follows:  Two  shafts  were  sunk  on  the  ridge  of  the  reef  and  from 

42 


EXCAVATION  OF  SUBAQUEOUS  ROCKS— BY  A  LARGE  BLAST  43 

-iff 

these  shafts  two  sets  of  parallel  galleries  were  run  at  right  angles 
to  each  other,  undermining  the  whole  nine  acres  of  reef  and  leaving 
it  standing  on  pillars  about  15  ft.  square  and  about  25  ft.  center  to 
center.  The  roof  in  the  cross  galleries  was  then  blasted  down, 
leaving  it  as  thin  as  the  character  of  the  rock  and  the  location  under 
the  river  bed  would  permit.  The  average  thickness  of  the  roof 
was  18.8  ft.,  while  the  least  thickness  was  10  ft.  As  the  soundings, 
although  taken  with  great  care,  could  hardly  indicate  the  difference 
between  rock  conglomerates  and  boulders,  the  cutting  of  the 
roof  of  the  small  galleries  was  carried  on  with  great  caution.  Only 
one  drill  hole  was  fired  at  a  time,  thus  requiring  a  large  expenditure 
for  both  drilling  and  explosives;  2.3  pounds  of  explosives  and  11.97 


FlG-  10.— Plan  of  Flood  Rock  at  Hell  Gate,  N.  Y. 

ft.  of  drilling  were  required  per  cu.yd.  The  height  of  the  galleries 
varied  from  4  to  33  ft.,  while  they  were  10  ft.  wide.  Fig.  10  shows 
the  honeycombing  of  the  Flood  Rock.  The  rock  was  fissured  and 
an  inrush  of  water  was  only  prevented  by  walling  the  seams  with 
Portland  cement.  The  seams  gave  continuous  trouble  until  the 
work  was  completed.  The  amount  of  work  required  to  undermine 
the  reef  consisted  of  21,669  ft.  of  tunnels  driven,  80,232  cu.yds.  of 
rock  excavated,  and  about  480,000  Ibs.  of  high  explosives  consumed. 
Only  one  man  was  killed  during  the  operations. 

It  was  the  intention  of  Gen.  Newton  to  excavate  a  cavity  suf- 
ficiently large  to  receive  the  debris  from  the  roof  and  leave  a  depth 
of  26  ft.  at  mean  low  water,  after  the  final  blast.  But  on  account 
of  the  extra  expense  of  timbering  and  the  fact  that  it  required  1.45 
cu.yds.  of  space  to  contain  one  cu.yd.  of  roof  after  it  was  broken, 


44 


A  TREATISE  ON  DREDGES   AND   DREDGING 


this  part  of  the  project  was  modified,  as  it  was  believed  that  the 
required  depth  could  be  obtained  more  economically  by  dredging 
.a  portion  of  the  debris. 

After  the  completion  of  the  galleries,  the  roof  and  the  pillars 
were  drilled  to  a  depth  of  33  ft.  below  mean  low  water,  with  holes 
enough  to  contain  0.79  of  a  pound  of  No.  1  dynamite  for  every 
cu.yd.  of  rock  and  every  7000  pounds  of  water  overhead,  amounting 
to  1 .04  pounds  per  cu.yd.  of  rock  broken.  The  holes  drilled  upward 
were  at  angles  of  60  and  45  degrees,  the  former,  along  the  center  of 
the  gallery  (see  Fig.  11),  were  8  ft.  deep,  the  latter  10  ft.,  so  as  to 
reach  as  far  over  the  pillars  as  possible.  These  lengths,  however, 
were  often  reduced  by  the  drill  cutting  into  seams  open  to  the  river. 


FIG.  11. — Honeycombing  of  Flood  Rock,  showing  the  Direction  of  Drill  Holes  in 

Galleries. 


The  holes  were  of  such  a  diameter  as  to  receive  a  rigid  2  J-inch  cart- 
ridge throughout  their  entire  length,  and  altogether  113,102  ft.  of 
such  holes  were  required. 

An  elaborate  set  of  experiments  was  planned  and  carried  out 
in  order  to  obtain  more  simple  methods  of  firing  the  mine  and  to 
extend  the  list  of  available  explosives,  which  was  then  practically 
limited  to  dynamite  or  other  nitroglycerine  compounds.  These 
experiments  resulted  in  proving  that  all  the  electrical  connections 
between  the  drill  holes  and  the  battery  could  be  dispensed  with,  as 
the  explosion  of  a  few  pounds'  charge  of  dynamite  would  fire  with 
absolute  certainty  under  water  another  charge  of  dynamite  packed 
in  a  thin  elastic  envelope  at  a  distance  of  27  ft.  They  also  proved 
the  efficacy  of  firing  long  narrow  charges  of  rackrock,  an  explosive 
so  inert  and  so  safe  to  handle  that  a  pistol  bullet  may  be  shot  into 


EXCAVATION  OF  SUBAQUEOUS  ROCKS— BY  A  LARGE  BLAST    45 

it  at  short  range  with  impunity.  This  explosive  was  afterward 
adopted  for  the  great  blast,  its  strength  under  water  being  somewhat 
greater  than  that  of  No.  1  dynamite.  It  cost  a  little  more  than 
half  of  No.  1  dynamite  and  had  the  great  advantage  that  it  could 
be  stored  in  large  quantities  without  danger  to  the  city,  as  it  was 
made  explosiblo  just  before  being  taken  to  the  mine. 

The  rackrock,  consisting  of  79  parts  of  finely  ground  chlorate  of 
potash  and  21  parts  of  di-nitrobenzole,  was  mixed  in  small  batches 
in  a  leaden  trough  and  packed  at  once  into  cartridge  cases  2J  in. 
in  diameter  and  24  in.  long,  made  of  copper  0 . 005  of  an  inch  thick. 
Into  each  cartridge  was  inserted  a  small  exploder  containing  30 
grains  of  fulminate,  reinforced  by  one  ounce  of  dynamite.  The 
cartridge,  being  loaded  its  lid  was  securely  soldered,  using  an  alloy 
melting  at  160°  F.  and  a  hollow  soldering  iron  heated  by  blowing 
through  it  a  jet  of  wet  steam.  In  all  42,528  cartridges  were  thus 
soldered  without  accident. 

All  the  loading  in  the  mines  was  done  by  a  gang  of  12  men,  who 
first  placed  the  rackrock  cartridges,  ending  with  one  of  dynamite 
containing  the  fulminate  exploder,  besides  the  usual  brass  wires, 
which  were  secured  by  means  of  wooden  wedges.  The  number  of 
pounds  of  rackrock  put  in  drill  holes  was  240,399;  of  dynamite, 
4331;  total,  284,730  pounds  of  explosives.  There  were  11,789  drill 
holes  in  the  roof  and  772  in  the  pillars.  To  prevent  the  cartridges 
from  slipping  out  of  the  inclined  holes  the  exterior  of  the  cartridges 
was  provided  with  short  brass  wires  spreading  out. 

The  primary  charges  which  were  to  fire  those  in  the  drill  holes 
were  placed  along  the  galleries  at  intervals  of  25  ft.  They  consisted 
of  two  24  X 1  J-inch  thin  copper  cartridges  filled  with  No.  1  dynamite, 
packed  solidly  and  lashed  upon  a  horizontal  beam  at  a  height  above 
the  floor  varying  from  3  to  12  ft.  according  to  the  height  of  the 
galleries.  On  top  of  these  was  lashed  a  rigid  brass  shell  8-12  in., 
containing  about  one-half  pound  of  dynamite  put  in  loose  and  a  plat- 
inum wire  connected  by  wires  with  the  battery  at  the  head  of  the 
shaft.  There  were  591  of  these  primary  charges  arranged  in  21 
circuits  of  25  each,  and  three  circuits  of  22  all  coming  together  at 
the  poles  of  the  batteries.  Some  of  these  circuits  were  nearly  one 
mile  long. 

The  battery  was  composed  of  60  cells  all  coupled  in  one  series, 
two  large  mercury  cups  constituting  the  poles.  The  24  lead  wires 
dipped  into  one  of  these  cups  and  the  24  return  wires  terminated 


46  A  TREATISE  ON  DREDGES  AND   DREDGING 

in  a  third.  Between  this  third  cup  and  the  remaining  pole  of  the 
battery  stood  the  circuit  closer,  composed  of  an  iron  cup  containing 
mercury  in  which  sat  a  thin  glass  tumbler  partially  filled  with  mercury. 
The  leading  wires  were  connected  with  the  mercury  in  the  iron  cup 
while  the  returning  wires  were  connected  with  the  mercury  of  the 
tumbler.  To  close  the  circuit  it  was  only  necessary  to  break  the 
glass  tumbler.  An  iron  rod  J  in.  in  diameter  and  4  ft.  long  terminated 
with  a  disk,  was  used  for  this  purpose. 

When  all  the  work  was  completed  the  mine  was  flooded  and 
the  blast  was  fired  at  11.13  A.M.,  October  11,  1885.  The  explosion 
occurred  over  the  whole  area  of  the  reef.  There  was  no  loud  report 
and  no  dangerous  shock  through  the  earth,  though  a  slight  vibration 
was  observed  as  far  away  as  Cambridge,  Mass.  A  few  panes  of 
glass  were  broken  in  the  neighborhood,  a  number  of  loose  ceilings 
came  down  and  several  bricks  were  shaken  from  a  chimney  of  a 
house  near  the  water's  edge  in  Astoria.  This  wras  all  the  damage 
done.  Soon  after  the  explosion  a  diver  was  put  down  and  found 
the  rock  was  cracked  and  shattered;  the  surface  blocks  very  large, 
but  in  good  shape  to  be  dredged  with  reasonable  amount  of  surface 
blasting.  Immediately  two  grapple  dredges  were  set  to  work  and 
they  removed  120  tons  per  day. 

The  total  cost  of  the  work  was  estimated  at  $2.99  per  cu.yd. 
of  rock  broken. 

Lift  Holes.  The  method  of  removing  the  subaqueous  rock  by 
a  large  single  blast  resulting  from  the  simultaneous  firing  of  long 
lift  holes  driven  from  a  pit  inclosed  by  a  coffer-dam  was  recently 
employed  at  Henderson's  Point  at  the  Portsmouth  Navy  Yard  in 
New  Hampshire,  an  account  of  which  was  published  in  the  Engineer- 
ing News,  August  3,  1905;  from  which  the  following  description  is 
taken : 

Henderson's  Point  was  a  ledge  of  trap  rock  400  ft.  wide  at  the 
base  and  projecting  300  ft.  into  Portsmouth  Harbor  hi  such  a  manner 
as  to  make  it  extremely  difficult  for  large  war  vessels  to  reach  the 
new  drydock.  The  area  of  rock  to  be  excavated  below  low  water 
was  about  three  acres,  and  the  contractors  decided  to  build  a  coffer- 
dam, horseshoe  shape,  and  excavate  all  the  rock  possible  within  this 
coffer-dam  by  ordinary  methods.  By  doing  this  a  rim  of  rock  was 
left  under  the  coffer-dam  and  extending  out  beyond  it  into  the  harbor. 
This  rim  of  rock  contained  approximately  35,000  cu.yds.  which  was 
broken  up  by  a  single  large  blast.  Figs.  12  and  13. 


EXCAVATION  OF  SUBAQUEOUS  ROCKS— BY  A  LARGE  BLAST     47 

The  contractors  decided  to  undermine  the  coffer-dam  by  drilling 
long  lift  holes,  using  the  large  Ingersoll -Sergeant,  Hg  submarine 
drills  mounted  on  timbers  laid  in  the  bottom  of  the  pit  excavated 
inside  the  coffer-dam.  In  this  way  203  lift  holes,  having  a  dip  of 
1  in  10  from  the  horizontal,  were  drilled  50  to  79  ft.  deep  and  5  ft. 


FIG.  12.— Plan  of  the  Ledge  of  Rock  at  Henderson's  Point. 

apart,  all  around  inside  of  the  pit.  The  holes  started  5  ft. 
below  the  bottom  of  the  grade  to  which  dredging  must  be 
carried,  so  as  to  make  sure  of  leaving  no  hog  backs  after  blasting. 
Fig.  13. 

The  diameter  of  the  holes  at  the  collar  was  6  in.  and  the  deepest 


FIG.  13. — Method  of  Excavation  followed  at  Henderson's  Point. 

holes  were  2  in.  in  diameter  at  the  bottom.  A  cross  bit  was 
used  for  starting  a  hole,  but  plain  chisel  bits  were  found  very 
effective  for  the  greater  depths.  The  rock  was  exceedingly  seamy, 
many  hard  quartz  veins  occurring  at  frequent  intervals  in  some 
holes. 

The  average  progress  of  drilling  was  30   ft.   per  10-hour  shift, 


48  A  TREATISE  ON  DREDGES   AND   DREDGING 

but  in  very  seamy  soil  this  quantity  was  greatly  reduced,  being 
at  times  not  more  than  10  ft.  per  10-hour  shift.  Eight  Ingersoll- 
Sergeant  and  two  Sullivan  drills  having  5^  in.  cylinders  were  used  for 
this  work.  Each  drill  was  mounted  on  wooden  blocking  bolted  to 
two  lines  of  sills  bedded  in  the  bottom  of  the  pit.  An  extension 
clinch  was  used  to  facilitate  the  handling  of  the  drill  steel,  by  giving 
plenty  of  clearance  between  the  drill  and  the  face  of  the  rock 
ledge. 

The  long  lift  holes  were  charged  with  dynamite.  At  first  the 
sticks  of  dynamite  were  inclosed  in  tin  tubes,  but  owing  to  the 
tendency  of  these  tin  tubes  to  catch  on  irregularities  in  the  sides 
of  the  hole  it  was  decided  to  use  only  plain  paraffined  paper  cartridges. 
These  dynamite  sticks  were  24  to  30  in.  long  and  made  in  four  sizes 
to  fit  the  taper  of  the  drill  hole,  2J,  3,  3J  and  4  in.  in  diameter. 
About  38  tons  of  dynamite  was  used  for  charging  203  lift  holes,  and 
it  was  furnished  by  the  National  Powder  Co.  of  New  York.  Nearly 
half  of  the  quantity  had  60  per  cent  of  nitroglycerine  and  the  balance 
75  per  cent.  Since  it  was  expected  that  some  of  the  dynamite  would 
be  under  water  three  weeks  before  the  firing  of  the  blast,  the  manu- 
facturers wrapped  each  stick  with  two  layers  of  paraffin  paper  and 
afterward  coated  the  sticks  with  a  paraffin  composition. 

Nine  hundred  electric  exploders  were  used,  especially  constructed 
for  subaqueous  work  by  the  Star  Electric  Fuse  Works  of  Wilkes- 
Barre,  Pa.  To  fire  the  exploders  there  were  used  110  volts  and  75 
amperes,  the  900  exploders  being  divided  into  45  groups  of  20  each. 
The  20  exploders  were  joined  together  in  series.  Each  of  these  45 
groups  was  joined  parallel  to  the  main  wires.  By  this  method  of 
wiring  every  exploder  received  1J  amperes. 

The  firing  station  was  located  1000  ft.  away  from  the  nearest 
point  of  the  coffer-dam,  in  which  a  breach  was  made  at  low  tide, 
in  order  to  flood  the  pit  and  thus  secure  a  water  tamping,  as  well 
as  cushion  to  take  up  the  shock  of  the  explosion.  Even  at  high 
tide  there  were  a  few  parts  of  the  rock  ledge  visible.  The  blast 
was  fired  at  4.10  P.M.  Sections  of  the  coffer-dam  fell  in  the  water 
at  a  distance  that  appeared  to  be  nearly  800  ft.  away  from  their 
original  position.  A  huge  column  of  water,  timber  and  rock  rose 
to  a  height  of  perhaps  150  ft.  and  at  the  same  time  a  sort  of  tidal 
wave  rushed  across  the  narrow  800-ft.  channel  to  a  height  of  several 
feet.  The  shock  was  scarcely  felt  by  those  at  any  considerable 
distance,  for  the  explosive  appeared  to  have  expended  nearly  all 


EXCAVATION  OF  SUBAQUEOUS  ROCKS— BY  A  LARGE  BLAST    49 

its  energy  in  breaking  rock.  Not  a  single  accident  marred  the 
enterprise  and  the  office  building  300  ft.  away  from  the  blast  was 
uninjured. 

The  work  was  carried  out  by  the  Massachusetts  Contracting  Co. 
of  Worcester,  Mass.,  with  Mr.  O.  A.  Foster  as  superintendent  in 
charge,  while  Lieut.  Luther  E.  Gregory,  U.  S.  N.,  was  the  engineer 
in  charge  for  the  government. 


CHAPTER  VII 
HINTS   ON   SELECTING   DREDGES   FOR   VARIOUS   WORK 

NOTHING  is  more  important  than  the  selection  of  the  style  and 
size  of  a  dredge  to  be  used  on  a  job.  Thousands  of  dollars  have 
been  wasted  by  errors  in  judgment  made  in  this  regard,  or  from 
ignorance  on  the  subject.  Only  a  few  years  ago  the  writer  saw  a 
mistake  made  of  this  kind  that  proved  expensive  to  all  concerned.  It 
is  almost  impossible  for  a  novice  to  decide  knowingly  in  such  a  matter. 
Not  only  must  one  be  conversant  with  the  various  styles  or  type 
of  dredges  made  and  used,  but  the  work  they  will  do  and  their 
general  adaptability  must  be  known.  Even  then  it  is  not  always 
possible  to  select  a  dredge  suitable  from  those  already  in  use,  but 
it  is  frequently  necessary  to  design  a  special  machine,  to  do  the 
proposed  work  in  an  economical  manner. 

At  times,  though,  only  some  detail  of  the  dredge  has  to  be  changed 
to  adapt  it  to  the  work.  In  America,  both  engineers  and  contractor 
make  the  serious  blunder  of  attempting  to  use  a  dredge  already  at 
hand,  instead  of  rebuilding  it,  or  getting  another  machine,  believing 
that  either  by  their  determination  or  by  their  ingenuity  they  can 
make  the  machine  in  question  do  the  dredging  economically. 

Although  it  is  true  that  many  dredges  of  special  design  are  copied 
in  part  from  older  types,  yet  no  one  but  those  of  experience  in  dredge 
building  and  operation  should  attempt  to  design  machines.  There 
are  some  monumental  piles  of  junk  in  existence  due  to  poor  designing, 
and  in  some  cases  profits  are  quickly  eaten  up  in  repairs  due  to  the 
same  reason.  Dredges  must  not  only  be  designed  well,  but  must  also 
be  well  constructed. 

There  are  three  important  considerations  that  should  be  given 
the  selection  of  a  dredge :  First,  the  character  of  the  soil  or  material 
to  be  excavated.  Second,  the  method  to  be  used  in  the  disposal 
of  the  material  and  the  distance  from  the  point  of  dredging,  to  the 
place  of  deposit.  Third,  the  local  conditions  that  may  surround  th« 
work,  such  as  whether  harbor  or  river  improvement,  the  traffic 

50 


HINTS  ON  SELECTING  DREDGES  FOR  VARIOUS  WORK       51 

that  may  interfere  with  the  dredges,  whether  it  is  dredging  to  reclaim 
land,  or  to  deepening  channels,  and  many  other  considerations  of 
this  character.  One  important  item  is  the  depth  of  the  water  and 
the  probable  chance  of  storms. 

The  character  of  the  soil  has  much  to  do  with  the  general  type 
of  dredge  to  be  selected,  as  whether  a  hydraulic  dredge,  a  ladder  or 
dipper  type  is  to  be  used. 

The  suction  or  hydraulic  dredge  is  better  suited  to  work  in  soil 
or  material  that  is  homogeneous,  mattering  but  little  whether  it  is 
soft  or  compact,  but  it  should  not  be  excessively  hard.  Such  materials 
are  sand,  clay,  earth,  gravel  and  alluvial  deposit,  that  are  free  from 
large  obstructions  as  boulders,  snags,  stumps  and  such  things  that 
are  not  readily  broken  up  with  the  cutter  or  agitator. 

When  the  material  or  soil  is  very  compact  and  contains  much 
large  gravel  or  small  boulders,  or  is  tough  hardpan,  ladder  dredges 
are  better  adapted  than  the  suction  dredge.  Extremely  large  boulders 
cannot  enter  the  buckets  so  the  ladder  dredge  must  excavate  around 
them,  leaving  them  to  be  taken  out  by  other  means. 

Grapple  dredges  will  work  in  either  hard  material  or  in  soft  soil, 
but  more  efficient  work  is  done  when  the  material  is  homogeneous. 

When  the  material  is  full  of  obstruction,  whether  the  great  mass 
is  soft  or  compact  the  dipper  dredge  is  the  most  efficient  machine 
in  use. 

When  the  material  is  such  that  it  can  be  pumped  through  pipes 
to  the  place  of  disposal,  the  suction  dredge  is  ideal,  unless  the  line 
of  discharge  pipe  interferes  with  the  traffic.  If  the  distance  to  trans- 
port the  dredged  material  is  very  short,  a  high  tower  ladder  dredge 
with  a  long  chute  can  be  used,  but  generally  speaking  when  a  ladder 
dredge  is  used  scows  or  barges  are  necessary  to  transport  the  exca- 
vated material.  For  both  the  grapple  and  dipper  dredge  scows  are 
necessary  unless  the  dredged  material  is  deposited  behind  a  nearby 
bulkhead  or  is  carried  away  by  a  system  of  belt  conveyors. 

When  the  water  is  rough  at  the  site  of  dredging,  or  if  the  scows 
or  pipe  line  interfere  with  the  traffic  of  vessels,  then  the  self -contain- 
ing or  hopper  type  of  dredge  should  be  used.  The  hydraulic  hopper 
dredge  and  the  ladder  hopper  dredge  as  well  as  the  combination 
dredge  are  all  described  in  this  treatise. 

As  a  rule  hopper  dredges  are  sea-going  vessels.  In  ordinary 
weather  they  can  work  without  anchorage.  The  dredge  passes  slowly 
over  the  area  to  be  dredged,  picking  up  its  load,  and  when  the  hoppers 


52  A  TREATISE  ON   DREDGES   AND   DREDGING 

are  full  lifts  its  suction  pipe  or  its  ladder  and  proceeds  to  sea  to 
dump  its  load.  This  style  of  dredge  is  not  well  adapted  for  material 
or  soil  that  does  not  settle  or  precipitate  in  the  hoppers. 

When  scows  or  barges  are  used  the  ladder  dredge  is  well  adapted, 
especially  for  hardpan  or  similar  material.  In  Europe  this  machine 
is  used  on  all  kinds  of  work  both  wet  and  dry.  It  was  used  exclusively 
on  the  Suez  Canal  and  also  on  some  of  the  European  canals,  and  in 
open  channels,  when  large  quantities  of  earth  have  to  be  excavated 
over  large  areas  it  is  well  adapted,  as  it  gives  a  true  and  level  bottom. 
This  type  of  machine  is  not  easily  affected  by  tides  or  currents,  and 
although  it  will  excavate  more  cubic  yards  per  horse  power  than  any 
other  type,  yet  for  working  in  confined  places,  and  under  trying 
circumstances,  and  for  power,  speed  and  general  adaptability  it 
will  not  compare  with  the  dipper  dredge  so  generally  used  in  America. 

A  great  advantage  of  the  dipper  type  is  in  economy  of  labor.  It 
is  able  to  handle  boulders,  stumps  and  other  obstructions,  owing  to 
its  great  strength  and  power,  and  to  the  fact  that  it  is  held  to  its 
work  by  means  of  powerful  spuds.  This  machine  has  a  great  range 
of  adaptability,  as  it  will  dig  at  depths  of  40  ft.  or  more,  load  scows 
or  cast  material  upon  the  bank. 

This  dredge,  as  well  as  the  grapple  or  clamshell  dredge,  depends 
upon  the  operator  for  its  speed.  Everything  being  equal,  a  skilled 
operator  will  excavate  more  material  than  a  less  experienced  man. 
Thus  it  is  important  that  the  operator's  work  be  made  as  easy  as 
possible  and  all  levers  should  be  located  conveniently  and  be  easily 
controlled.  Grapple  dredges  cannot  excavate  as  hard  material 
as  a  dipper  machine,  but  they  can  work  at  a  greater  depth.  Spuds 
and  anchors  are  used  to  hold  the  dredge  in  place  in  the  same  manner 
as  with  a  dipper  machine. 

Hydraulic  dredges  are  especially  adapted  to  excavate  homo- 
geneous material  in  large  quantities,  when  the  pipe  line  is  not  over 
3000  ft.  long.  With  a  greater  length  of  pipe  a  large  per  cent  of  the 
power  is  absorbed  by  friction  in  the  pipes.  Clay  material  shows 
less  wear  on  the  pipe  than  sand,  and  a  larger  per  cent  of  solid  material 
is  carried  when  clay  is  excavated.  The  most  important  point  is 
the  cutter  or  agitator.  The  simplest  agitator  is  a  bird-cage  affair 
used  on  small  dredges  for  sand.  Revolving  first  in  one  direction 
and  then  in  the  other  the  sand  is  stirred  up  enough  to  become  mixed 
with  water  and  the  suction  from  the  pump  lifts  the  sand  and  water. 
As  fast  as  a  hole  is  made  in  the  sand,  the  mass  of  sand  keeps  caving 


HINTS  ON  SELECTING  DREDGES  FOR  VARIOUS  WORK       53 

in,  thus  feeding  the  sand  to  the  pump.  For  harder  material  the 
agitator  is  equipped  with  knives,  which  cuts  the  material  as  they 
revolve.  For  stiff  and  heavy  clay  and  harder  material  sufficient 
.  space  must  be  left  between  the  blades  for  large  lumps  of  clay  and 
small  boulders  to  enter  the  suction  pipe.  The  cutter  must  not  only 
be  of  great  strength,  but  must  be  so  attached  to  the  suction  pipe 
as  not  to  be  easily  detached  by  the  great  strain  that  comes 
upon  it. 

Neither  the  hydraulic  dredge  nor  ladder  type  can  handle  anything 


FIG.  14. — Stone  Lifter  on  St.  Lawrence  River. 


in  the  way  of  rock  except  small  boulders.  The  limit  is  smaller  with 
the  hydraulic  dredge  than  with  the  endless  chain  or  ladder  dredge. 
A  dipper  dredge  can  handle  rock  and  boulders  of  several  yards  in 
size,  and  the  grapple  dredge  can  also  handle  rock  and  boulders 
when  fitted  with  a  special  stone  grapple.  But  with  any  type  of 
dredge  large  stones  or  boulders  must  be  broken  up  before  they  can 
be  removed  by  dredges.  At  some  places  there  are  now  used  stone 
scows  or  lifters.  Fig.  14  is  an  illustration  of  such  a  machine  used 
by  the  Canadian  Government  on  the  St.  Lawrence  River.  This 
stone  lifter,  by  means  of  its  stone  hooks  or  grabs,  will  raise  boulders 
weighing  as  much  as  50  tons. 


54  A  TREATISE  ON  DREDGES   AND   DREDGING 

Hydraulic  and  ladder  dredges  can  by  cutting  up  snags,  logs, 
stumps  and  such  obstructions  remove  them,  but  they  are  ill  suited  for 
such  work.  The  dredge  that  will  remove  these  better  than  any  other 
is  the  dipper  machine.  The  great  pull  of  the  hoisting  engines  on  the 
dipper,  when  it  catches  under  a  snag  or  log  will  raise  it  up  even  when 
covered  with  a  foot  or  two  of  soil.  In  excavating  the  shallow  canals 
through  the  Dismal  Swamp  in  Virginia  and  North  Carolina,  great 
numbers  of  logs  and  stumps  were  encountered  and  dipper  dredges 
were  used  exclusively  on  this  work.  However,  owing  to  the  excessive 
number  of  sunken  logs  encountered,  the  work  proved  very  expensive, 
and  some  of  the  contractors  lost  money,  due  to  this  cause.  On  the 
Mississippi  River  snag-pulling  machines  are  used  for  removing  old 
snags  and  logs,  making  it  possible  for  hydraulic  dredges  to  follow 
up  these  machines. 

For  some  jobs  not  only  must  special  dredges  be  designed,  as 
previously  stated,  but  it  is  sometimes  necessary  to  design  special 
pipe  lines,  scows  or  even  hoppers,  in  order  to  carry  on  the  work 
economically. 

It  is  almost  impossible  to  give  any  rule  for  selecting  a  dredge 
for  canal,  channels  in  large  bodies  of  water,  for  rivers,  harbors  and 
other  improvements.  The  soil,  the  disposal  of  the  material  and 
local  conditions  must  govern  it.  All  of  the  types  of  machines  here 
listed  are  and  can  be  used.  Sometimes  on  one  job  in  America 
hydraulic,  ladder  and  dipper  dredges  have  been  used.  Some  have 
also  been  of  the  hopper  type,  and  some  were  self-propelling,  while 
others  were  non-propelling. 

In  narrow  canals  dipper  dredges  are  often  used,  depositing  the 
material  on  either  bank.  In  wide  streams  scows  are  used  to  take 
the  spoil  both  from  dipper  and  grapple  dredges.  For  rivers  and 
harbors  and  for  channels  in  bays  and  lakes  all  styles  of  machines 
are  used.  For  filling  in  behind  bulkheads  and  for  reclaiming  low 
lands  the  hydraulic  dredge  is  a  favorite  machine,  as  the  great  quan- 
tity of  water  distributes  the  material  over  a  large  area.  When 
bulkheads  are  not  built,  dipper  machines  are  first  used  to  throw 
up  a  dike  or  levee  and  then  a  hydraulic  machine  for  depositing  the 
material  behind  the  dyke. 

Often  dredged  material  has  to  be  handled  twice.  It  may  be 
first  loaded  onto  scows,  then  dumped,  and  handled  again  to  be  placed 
behind  bulkheads,  walls,  or  into  piers.  This  rehandling  is  sometimes 
done  with  suction  dredges  or  by  bucket  machines.  At  times  hopper 


HINTS  ON  SELECTING  DREDGES  FOR  VARIOUS  WORK      55 

scows  are  used  and  the  material  pumped  directly*  from  the  scows. 
As  a  rule  the  second  handling  generally  costs  more  than  the  first. 

When  dredges  work  in  sheltered  harbors  or  in  rivers  and  canals 
it  is  not  necessary  to  have  them  self-propelling,  but  when  they  are 
used  in  exposed  places  or  go  to  sea  it  is  safer  to  have  a  self-propelling 
machine.  Many  large  dredges  are  self-propelling  even  when  designed 
for  river  work,  as  it  is  more  economical  to  move  them  great  distances 
without  the  aid  of  tugs  and  it  is  easier  to  maneuver  them  while 
at  work. 

Non-propelling  dredges  are  handled  when  at  work  by  means 
of  spuds  and  by  anchor  lines.  For  small  dredges  the  lines  are 
handled  by  small  rowboats  and  capstans  on  the  deck  of  the  dredge, 
but  for  large  machines  anchor  scows  are  sometimes  used.  These 
are  small  scows  with  a  windlass  and  capstan  on  it  to  handle  the 
heavy  anchors,  and  the  lines  are  run  from  the  scows  to  the  dredge. 

When  anchor  lines  are  used  the  maneuvering  of  the  dredge  while 
at  work  must  always  be  planned  so  as  not  to  interfere  with  the  passing 
of  vessels.  The  work  should  be  done  so  that  delays  happen  neither 
to  the  dredge  nor  to  the  vessels. 


CHAPTER  VIII 

DREDGING  CREWS,   THEIR   QUARTERS,   AND   TENDERS   FOR 

DREDGES 

THE  size  of  a  crew  needed  to  operate  a  dredge  varies  exceedingly, 
according  to  the  type  and  size  of  the  dredge.  The  wages  of  men 
likewise  vary  in  different  sections  of  the  world.  Generally  speaking 
most  dredgemen,  especially  when  they  live  on  board  the  boat,  are 
paid  monthly  salaries.  However,  some  are  paid  wages  by  the  day. 
As  dredges  are  used  to  a  great  extent  on  government  work,  the 
working  hours  of  a  shift,  especially  in  America  are,  as  a  rule,  8  hours. 
Thus  to  work  continuously  night  and  day,  three  crews  are  needed. 

In  the  United  States  the  Federal  Courts  have  decided  that 
dredgemen  are  seamen,  so  that  laws  affecting  seamen  apply  to 
dredgemen. 

When  dredges  are  worked  in  fleets  or  more  than  one  is  engaged 
on  a  single  improvement  a  superintendent  or  general  manager  is  in 
charge  of  all  the  machines.  Under  him  is  a  captain  for  each  dredge, 
under  whom  on  large  machines  are  several  officers  as  assistants, 
who  are  in  charge  of  the  different  shifts.  Then  there  are  employed 
engineers  and  assistant  engineers,  and  a  chief  fireman  and  assistants. 
In  some  sections  operators  known  as  levermen  are  employed,  and 
on  large  dredges  there  are  always  several  oilers  or  greasers ;  other- 
wise the  machinery  is  not  kept  well  lubricated. 

There  are  also  employed  laborers,  known  as  deckhands,  linesmen 
or  sailors.  These  men  do  the  general  work  and  attend  to  the  lines, 
anchors,  spuds,  pipe  lines  and  other  details.  Scow  men  are  also 
employed,  being  used  either  on  the  anchor  scows  when  used  or  on 
the  scows  that  carry  away  the  dredged  material. 

On  the  largest  dredges  and  those  of  the  sea-going  type,  carpenters, 
machinists  and  blacksmiths  are  frequently  employed.  There  are 
also  watchmen  and  cooks  employed.  In  addition  to  all  of  these 
the  tugboats  have  their  necessary  crews. 

Some  small  hydraulic  dredges  used  for  loading  scows  with  sand 

56 


DREDGING  CREWS  AND  TENDERS  57 

for  commercial  purposes  are  worked  with  a  crew* of  only  2  or  3 
men.  Small  grapple  and  dipper  dredges  use  less  than  10  men.  The 
Canadian  Government  has  worked  one  dipper  dredge  for  a  number 
of  years  with  a  crew  of  9.  A  snag  boat  also  worked  by  the  same 
government  is  manned  with  a  crew  of  9.  The  hydraulic  dredge 
"King  Edward"  carries  a  crew  of  18  men,  while  the  large  hydraulic 
dredge,  "  J.  Israel  Tarte,"  used  in  St.  Peter's  Bay  on  the  St. 
Lawrence  River,  has  a  crew  of  35  for  night  and  day  work.  The 
elevator  or  ladder  dredges  used  on  the  same  river  carry  crews  of  28 
to  do  continuous  work  throughout  the  24  hours. 

The  American  sea-going  hydraulic  dredges  "Atlantic"  and 
"  Manhattan  ",  used  in  the  Ambrose  Channel  in  New  York  Bay, 
each  carries  a  crew  of  54  men  for  night  and  day  work. 

For  gold,  tin  and  platinum  dredging  the  crews  are  much  smaller. 
Hydraulic  dredges  for  such  purposes  are  not  extensively  used,  the 
ladder  type  being  preferred.  Mr.  Henry  G.  Granger  advocates  the 
use  of  a  specially  designed  suction  dredge  for  gold  mining  and  gives 
a  crew  of  6  men  to  manage  the  dredge  with  13  men  under  these 
in  each  shift.  Then  for  these  8-hour  shifts  39  men  will  be  needed 
besides  the  6,  making  45  men  in  all.  In  charge  of  this  crew  he 
has  a  general  manager  experienced  in  gold  saving.  The  others  are 
captain,  engineer  and  assistants,  firemen  and  assistants,  levermen, 
deckhands,  cook  and  general  helpers. 

In  the  Oroville  district  in  California  the  large  electrical  dredges 
excavating  from  100,000  to  200,000  cu.yds.  per  month  are  operated 
with  small  crews.  Over  each  machine  is  a  dredgemaster,  and  he 
has  6  men  under  him,  2  for  each  shift.  Besides  these  some  dredges 
use  a  man  on  the  ground  known  as  the  shoreman. 

When  crews  are  worked  in  or  near  large  cities,  quarters  are  not 
needed  for  the  men  on  the  dredges,  but  for  night  and  day  work  or 
for  dredges  at  sea  or  for  work  away  from  their  home  ports,  ample 
quarters  for  the  men  should  be  provided  on  the  boat.  Occasionally, 
as  on  the  St.  Lawrence  River,  such  quarters  are  built  on  scows  which 
are  anchored  near  the  dredge.  When  the  crew's  quarters  are  built 
on  the  dredge  they  are  generally  on  the  upper  deck  above  the  machin- 
ery. They  should  be  sanitary  and  comfortable  and  the  men  should 
have  a  good  mess  room  in  which  to  eat  their  meals.  The  food  fur- 
nished should  be  substantial,  of  a  pleasing  variety  and  well  cooked 
and  served.  When  men  are  well  fed  and  given  comfortable  quarters 
and  beds  they  in  return  give  efficient  service.  The  quarters  can 


58  A  TREATISE  ON   DREDGES   AND   DREDGING 

be  heated  by  steam  from  the  boilers,  and  lighted  by  electricity. 
There  should  also  be  a  room  furnished  to  dry  the  men's  clothing  and 
shoes.  Men  never  give  good  work  in  clothing  that  is  only  half  dry. 
Electric  lights  are  an  essential  for  night  work,  and  at  only  a  slight 
cost  the  entire  dredge  can  be  furnished  with  both  incandescent  and 
arc  lights.  An  electric  search  light  is  found  to  be  a  great  aid  in 
dredging,  as  anchor  scows  and  lines  can  be  watched  and  adjusted 
by  its  aid. 

Ample  provision  should  also  be  made  for  men  to  wash  and  bathe. 
When  coal  and  supplies  are  taken  on  the  dredge  the  helpers  get 
very  dirty,  and  a  bath  when  they  are  through  work  will  improve 
their  health. 

The  coal  bunkers  on  a  dredge  should  be  so  situated  that  the  coal 
can  be  fed  under  the  boilers  without  great  labor,  and  'so  the  bunkers 
can  be  refilled  from  scows  with  ease,  or  if  the  dredge  goes  to  a  dock 
for  the  coal,  so  it  can  be  placed  aboard  without  any  trouble. 

On  some  of  the  largest'  dredges,  especially  those  that  are  out  from 
port  for  some  days,  some  space  is  devoted  to  a  repair  and  black- 
smith shop.  This  frequently  means  the  saving  of  much  valuable 
time  and  money.  Where  a  number  of  dredges  are  working  close  to 
each  other  a  scow  is  sometimes  fitted  up  as  a  repair  shop  and  towed 
from  dredge  to  dredge  as  needed. 

Many  large  dredges  go  to  their  working  places  on  Monday  and 
remain  there  excavating  until  Saturday  evening,  when  they  return 
to  their  docks.  Dredging  is  not  done  on  Sunday,  but  new  supplies 
are  placed  aboard  and  needed  repairs  are  made.  Such  dredges  are 
generally  self-propelling.  Non-propelling  dredges,  as  a  rule,  remain 
anchored  at  the  site  of  their  work  over  Sunday. 

A  record  or  log  should  always  be  kept  of  the  movements  of  a 
dredge,  as  well  as  of  the  time  spent  in  dredging  and  the  delays  that 
occur  and  their  causes  and  such  details  as  are  found  essential.  Such 
records  are  generally  found  to  be  useful,  both  in  keeping  costs  of 
work  done  and  as  a  check  on  the  crews. 

Every  dredge  must  have  a  number  of  tenders  in  order  to  aid 
in  its  work.  This  is  even  so  with  sea-going  hopper  dredges. 

There  must  be  tugboats  of  great  power  and  entirely  seaworthy, 
also  scows  to  haul  the  dredge  material  and  supplies  as  coal,  pro- 
visions, etc.  Then  snagboats  and  stonelifters  are  often  needed,  and 
drilling  boats  for  drilling  rock  to  be  excavated.  Rockbreakers  too 
are  now  added  to  dredging  fleets.  When  hydraulic  dredges  are 


DREDGING  CREWS  AND  TENDERS  59 

used  a  large  number  of  pontoons  are  necessary  to  carry  the  discharge 
pipe.  Pontoons  or  scows  are  also  used  to  carry  belt  conveyors  when 
the  latter  are  used  to  transport  the  dredged  material. 

Launches  are  necessary  for  superintendents  and  engineers 
to  visit  the  dredges  and  oversee  the  work.  The  use  of  such  launches 
often  means  the  saving  of  much  time  and  money.  Every  dredge 
should  be  equipped  with  one  or  more  rowboats  for  the  sailors  or 
dredgemen  to  attend  to  the  anchors  and  do  other  work  in  them. 
Such  boats  should  be  flat-bottomed,  so  that  the  men  can  work  in 
them  without  overturning,  as  frequently  happens  with  round-bottom 
boats.  These  boats  should  be  heavy,  yet  not  too  heavy  for  one  man 
to  row  in  an  ordinary  sea.  They  should  be  arranged  for  both  rowing 
and  sculling. 


CHAPTER   IX 
CLASSIFICATION  AND   CAPACITIES   OF   DREDGES 

THERE  is  such  a  large  variety  of  dredging  machines  on  the  market 
that  it  is  not  very  easy  to  give  a  clear  classification  of  them.  Then, 
too,  when  the  details  of  the  various  machines  are  considered,  things 
look  more  discouraging;  since  machines  that  appear  to  be  almost 
equals,  vary  greatly  in  the  construction  of  their  different  parts. 
Such  a  wide  difference  is  caused  by  the  fact  that  dredges  are  usually 
designed  for  working  on  a  specified  improvement,  and  are  constructed 
to  satisfy  all  the  requirements  of  the  indicated  work.  As  there  are 
not  two  jobs  alike,  the  dredges  are  built  with  such  a  large  variety 
of  details  that  it  is  difficult  to  find  two  dredges  perfectly  identical  in 
every  respect. 

However,  dredges  can  be  divided  into  two  classes,  continuous 
and  intermittent;  the  former  removing  continuously  the  material 
from  the  bottom  of  the  body  of  water,  while  the  latter  engage  the 
bottom  at  intervals.  Continuous  dredges  are  of  four  different 
types:  the  ladder,  the  hydraulic,  the  stirring  and  the  pneumatic; 
while  the  intermittent  are  divided  into  only  two  classes,  the  dipper 
and  the  grapple  dredges. 

Each  one  of  these  different  types  of  dredges  can  be  subdivided 
again  into  various  groups.  All  preserving,  however,  the  principal 
characteristics  of  their  type. 

The  ladder  dredge  may  be  mounted  on  a  hull  constructed  not 
only  for  carrying  all  the  various  machines  and  housing  the  crew, 
but  containing  also  large  bunkers  where  the  excavated  materials  are 
stored,  while  being  transported  to  the  dumping  place.  This  type  is 
called  the  sea-going  ladder  hopper  dredge.  On  the  other  hand  the 
hulk  may  be  built  so  as  to  carry  everything  connected  with  the  ser- 
vice of  the  dredge,  while  the  excavated  materials  are  dumped  into 
scows,  and  thus  we  have  the  simple  ladder  dredge.  It  may  be  either 
self-propelling  or  stationary,  depending  upon  the  machines  that 
are  mounted  on  board  the  vesse  permitting  the  dredge  to  go 

60 


CLASSIFICATION  AND   CAPACITIES  OF  DREDGES  61 

from  one  place  to  another  under  her  own  power,  or  the  dredge  is 
moved  by  "means  of  mooring  lines  and  tugboats.  Stationary  ladder 
dredges  may  be  constructed  with  the  ladder  on  one  side  of  the 
vessel  or  along  the  longitudinal  axis  of  the  boat;  they  may  be 
built  with  towers  of  the  ordinary  height  or  with  high  towers  in 
order  to  convey  the  debris  to  distant  points  along  the  shores. 

Hydraulic  dredges  may  be  classified  as  sea-going,  which  are 
those  able  to  steam  from  place  to  place  under  their  own  power,  and 
those  employed  in  the  improvement  of  canals  and  rivers.  In  the 
sea-going  dredges  when  the  vessel  contains  large  spaces  for  storing 
the  debris,  it  is  called  the  sea-going  hydraulic  hopper  dredge;  but 
when  the  hull  is  constructed  similar  to  any  other  steamer  without 
reserved  space  for  the  debris  it  is  called  the  sea-going  hydraulic 
dredge.  The  hydraulic  dredges  employed  in  the  rivers  and  canals 
may  be  either  self-propelling  or  non-propelling,  the  latter  being 
the  most  commonly  used,  while  the  dredges  employed  in  the  improve- 
ments of  the  Mississippi  and  other  large  rivers  are  mostly  self- 
propelling.  These  dredges,  according  to  Mr.  W.  Robinson,  may  be 
classified  according  to  the  location  of  their  feeders  into  lateral, 
forward,  and  radial. 

The  process  of  removing  a  very  loose  soil  from  the  bottom  by 
agitating  the  light  particles  so  that  they  may  be  carried  away  by 
water  is  not  very  extensively  employed  at  present.  However,  this 
stirring  method  has  an  historic  interest  and  in  some  particular 
work  it  can  be  employed  with  advantage  even  to-day.  The  stirring 
of  the  material  at  the  bottom  may  be  obtained  by  means  of  different 
devices  which  will  be  described  later  on;  they  are:  the  harrows, 
the  propellers,  the  converging  revolving  screws,  jets  of  water,  com- 
pressed air,  etc. 

Pneumatic  dredges  can  still  be  considered  in  their  experimental 
stage.  Only  one  type  of  these  machines  has  been  built  so  far  and 
this  group  of  machine  has  no  subdivision. 

Dipper  dredges  present  more  uniformity,  both  in  the  general 
design  and  construction  than  any  other  type  of  dredge.  They 
differ,  however,  in  the  material  employed  in  the  hull,  in  the  dimension 
and  efficiency  of  the  machinery,  capacity  of  the  dipper,  length  of 
the  handle  and  consequently  depth  of  the  reach,  etc.  But  the  large 
variety  of  details  does  not  change  the  main  characteristics  of  the 
machine,  consequently  subdivision  cannot  be  made. 

Grapple  dredges  arc  of  two  different   types,  the  clamshell  and 


62        A  TREATISE  ON  DREDGES  AND  DREDGING 

the  orange-peel  bucket.  The  bucket  of  the  clamshell  dredge  is 
built  of  different  shapes,  depending  upon  the  materials  that  the 
machine  is  designed  to  work  upon.  Thus,  for  instance,  the  bucket  is 
made  up  of  tines  when  the  dredge  is  to  work  in  a  soil  full  of 
pebbles  or  small  boulders,  or  is  intended  to  pick  up  stones  that  have 
been  broken  up  by  blasting.  A  solid  bucket  with  the  edges  provided 
with  tines  is  used  in  connection  with  dredges  intended  to  work  in 
soils  that  are  hard  and  compact,  while  a  clamshell  bucket  without 
tines  is  used  for  working  through  very  loose  soils.  The  orange-peel 
bucket  of  the  grapple  dredge  cannot  be  subdivided,  being  always 
of  the  same  shape.  Both  types  of  dredges  vary  greatly  in  dimension 
of  machines,  although  they  are  similar  in  their  chief  characteristics. 

It  is  possible  to  divide  all  dredges  into  two  classes,  namely, 
self-propelling  or  non-propelling.  A  self-propelling  dredge  can 
be  moved  by  its  own  power,  but  when  not  provided  with  self-pro- 
pelling apparatus  dredges  are  moved  by  tugboats,  or  by  chains  or 
moorings.  All  the  sea-going  dredges  of  the  ladder  and  hydraulic 
type  are  self-propelling,  while  many  of  the  same  type  of  dredges 
as  well  as  those  of  the  dipper  and  grapple  type  are  usually  stationary 
or  non-propelling. 

Self-propelling  dredges  meant  for  harbor  and  river  work  are 
also  rigged  to  be  moved  by  hawsers  and  moorings,  or  by  means  of 
spuds. 

The  self-propelling  dredges  can  be  provided  with  motive  power 
sufficient  to  move  the  boat  while  the  dredging  operations  are 
going  on,  or  it  may  be  necessary  to  -stop  dredging  in  order  to 
furnish  the  power  for  the  propelling  apparatus.  In  other  words 
on  the  same  machine  the  advance  of  the  boat  and  the  dredging 
operations  can  be  made  either  simultaneously  or  alternately. 

As  stated,  all  the  sea-going  dredges  are  self-propelling  and  so 
are  some  of  the  dredges  of  small  dimensions  used  in  the  excavation 
of  rivers,  canals,  etc.  The  propelling  devices  vary;  for  instance,  in 
the  sea-going  dredges  it  generally  consists  of  one  or  two  propellers 
of  the  same  form  and  dimension  as  used  in  steamers  of  similar 
capacity.  However,  paddle-wheels  are  sometimes  used.  These 
may  be  located  on  each  side  of  the  boat  as  in  any  ordinary  side- 
wheel  boat  which  plies  on  the  large  rivers  and  bays.  Paddle-wheels 
are  not  extensively  used  on  dredges,  owing  to  the  fact  that  either 
the  dredging  or  discharging  apparatus  is  usually  located  on  the 
sides  of  the  boat.  The  propelling  device  may  consist  also  of  a  single 


CLASSIFICATION   AND  CAPACITIES   OF  DREDGES  63 

paddle-wheel  located  at  the  stern,  as  used  on  some  dredges  employed 
on  the  Mississippi  River,  and  in  the  dredge  "  Ed  ward  VII"  shown  in 
Fig.  37.  The  single  stern  wheel  may  also  be  provided  with  spikes, 
which  engage  the  soil  at  the  bottom  of  the  river  and  canal.  Special 
dredges  employed  by  the  French  Government  on  the  River  Rh6ne 
have  been  so  constructed. 

Dredges  may  also  be  grouped  according  to  the  manner  of  disposing 
of  the  excavated  materials.  Thus  the  dredges  may  discharge  the 
materials  into  hoppers  of  large  capacity  contained  in  their  hulls, 
thus  carrying  and  dumping  their  loads  in  deep  waters.  These  are 
the  sea-going  dredges  of  the  hopper  type.  Sometimes,  though,  the 
hull  may  be  only  large  enough  to  carry  the  required  machines  and 
coal  bunker  or  there  may  be  room  to  provide  accommodations  for  the 
officers  and  crew.  Then  the  dredged  material  is  disposed  of  in 
different  ways.  It  can  be  discharged  into  scows  to  be  dumped 
into  deep  water,  or  deposited  wherever  desired,  as  is  commonly 
done  with  the  ladder,  dipper  and  grapple  dredges.  The  material 
can  also  be  dumped  directly  alongside  the  dredged  channel,  thus 
using  it  to  form  a  levee.  This  method  is  used  with  the  dipper  and 
grapple  dredges  employed  in  cutting  canals  or  dredging  narrow 
rivers,  and  sometimes  even  with  ladder  dredges,  but  chiefly  with  those 
of  the  high-tower  type.  All  the  hydraulic  dredges  and  some  of  the 
ladder  dredges  working  through  very  loose  soils,  when  they  are  not 
of  the  hopper  type,  discharge  the  excavated  material  through  long 
line  of  pipes  using  it  for  filling  lowlands,  as  is  commonly  done 
in  reclaiming  low,  swampy  ground. 

The  simplest  manner  of  disposing  of  dredged  material  is  the  one 
used  in  connection  with  the  stirring  process.  This  consists  in  stirring 
up  the  material  at  the  bottom  of  the  water,  thus  bringing  it  to  the 
surface  by  agitation  and  by  allowing  the  velocity  of  the  water  to 
carry  it  away.  Such  a  method,  however,  although  very  convenient 
and  economical,  is  very  seldom  used,  as  it  requires  conditions  that 
cannot  be  controlled  by  the  engineer.  This  method,  though,  has 
been  used  on  the  Mississippi  River  and  in  the  harbor  of  Swansea  in 
England. 

There  are  many  dredges  built  of  special  design  or  meant  for 
some  particular  piece  of  work,  yet  even  when  used  on  land  they  can 
be  considered  under  the  classification  given.  The  main  consideration 
should  always  be  the  adaptability  of  dredge.  \ 

In  the  United  States  dredges  of  many  designs  are  used,  and  until 


64  A  TREATISE  ON  DREDGES   AND   DREDGING 

recent  years,  as  a  rule,  it  may  be  said  that  in  the  extensive  harbor 
and  river  improvements  only  two  types  of  dredges  have  been  used, 
these  being  the  single-bucket  dredge,  either  of  the  dipper  or  grap- 
ple type,  and  the  hydraulic  dredge.  The  former  is  used  in  the  exca- 
vation of  soils  that  are  hard  and  compact,  while  the  latter  is  employed 
in  very  loose  soils,  as  mud  and  sand.  The  powerful  ladder 
dredge,  so  extensively  used  in  all  the  foreign  countries,  has  had  but 
little  use  here.  Such  a  disregard  for  one  of  the  most  efficient  machines 
exposes  the  American  engineers  and  contractors  to  severe  criticism. 
Mr.  A.  W.  Robinson  has  given  some  reasons  that  have  induced 
the  American  to  use  these  two  types  of  dredges  in  preference  to  the 
ladder.  In  a  new  country  more  important  improvements  were 
required  at  first  than  dredging,  and  consequently  the  little  dredging 
that  was  occasionally  done  in  keeping  the  rivers  and  channels  open 
to  navigation  was  not  done  directly  by  the  Federal  Government, 
but  given  out  on  small  contracts.  Work  was  scattered  along  an 
extensive  sea  coast  and  done  at  different  times,  according  to  the 
necessity  of  the  improvements  and  the  small  appropriations  made. 
Consequently  the  contracts  were  small  and  there  was  no  certainty 
of  continuous  work.  Thus  the  dredging  contractors,  found  it  more 
advantageous  to  work  the  cheapest  machines  even  i^  it  life  was  short. 
For  this  reason,  until  very  recently  the  dredges  employed  in  this 
country  were  mostly  of  the  single-bucket  type,  as  the  original  cost 
was  small  and  they  were  very  efficient  and  easily  handled.  Besides, 
they  had  the  advantage  of  being  used  for  other  purposes  than 
dredging,  as  lifting  piles,  lowering  concrete  blocks,  raising  wrecks, 
lifting  boulders,  loading  scows,  etc.  The  attention  of  the  American 
manufacturers  has  been  devoted  to  the  construction  of  the  type  of 
dredges  that  were  in  demand.  When,  with  the  changed  conditions 
of  the  country  more  powerful  machines  were  required,  these  were 
constructed  on  the  lines  of  the  old  ones,  as  dredgemen  were  skillful 
in  their  handling  and  the  manufacturers  had  acquired  great  expe- 
rience in  their  construction. 

It  has  only  been  within  a  comparatively  few  years  that  the  merits 
of  the  ladder  dredge  has  been  recognized  in  America.  Even  to-day 
contractors  seem  loath  to  use  this  type  of  dredge.  However,  during 
the  past  decade  the  Canadian  Government  has  built  a  number  of 
such  dredges  for  use  on  the  St.  Lawrence  River,  and  the  Federal 
Government  has  rebuilt  and  used  with  great  success  some  of  the 
small  ladder  dredges  used  by  the  French  on  the  Panama  Canal. 


CLASSIFICATION  AND  CAPACITIES  OF   DREDGES  65 

These  rebuilt  dredges  have  by  their  work  on  the  canal  attracted  the 
attention  of  both  engineers  and  contractors.  The  great  field  for 
ladder  dredges  in  America  has  been  in  the  gold  mining  section 
of  the  Western  States.  Although  originally  used  for  this  purpose 
in  New  Zealand,  the  idea  was  brought  to  the  United  States,  and 
the  development  of  this  type  has  been  rapid.  The  buckets  have 
been  increased  in  size  until  some  of  the  latest  machines  use  buckets 
of  f  cu.yd.  capacity. 

The  hydraulic  dredge  is  comparatively  a  very  modern  machine. 
It  was  introduced  on  public  work  after  the  United  States  had  grown 
and  work  of  great  magnitude  was  necessary  to  keep  apace  with 
the  wonderful  progress  of  the  country.  The  navigable  channels 
were  widened,  the  rivers  and  harbors  deepened  to  accommodate 
the  modern  and  ever-growing  leviathan  of  commerce,  and  in  such 
work  the  hydraulic  dredges  were  found  to  be  the  most  convenient 
and  efficient.  They  were  used  extensively  in  the  harbors  and  bays 
along  the  Pacific  coast,  and  along  the  Atlantic  shores  they  have 
now  almost  supplanted  the  single-bucket  dredges  used  in  former 
days.  The  great  dredging  work  going  on  continuously  in  this  country 
in  the  last  few  years  has  aroused  great  competition  among  the 
contractors,  who  have  constructed  powerful  machines  so  to  as  obtain 
competitive  work  and  perform  it  at  the  smallest  cost.  Consequently 
in  America  are  now  found  the  largest  and  most  powerful  dredging 
machines  in  the  world.  But  hydraulic  dredges,  although  very  efficient 
in  sandy  soils,  are  not  so  efficient  in  hard  soils.  Heretofore  such  soil 
has  been  excavated  by  the  bucket  type  of  dredge. 

The  capacity  of  dredges  varies  exceedingly,  and  it  is  difficult  to 
give  data  as  to  the  amount  of  material  that  can  be  excavated  by 
dredges  of  different  types.  The  character  of  the  material,  the  depth 
of  the  water,  the  current  and  amount  of  traffic  in  the  river,  harbor 
or  channel,  the  size  of  the  engines  on  the  dredges,  the  size  of  the 
pumps,  buckets,  or  dippers — all  of  these  conditions  and  many  more 
affect  the  amount  of  work  done. 

For  instance  a  small  elevator  or  ladder  dredge  of  the  hopper 
type  excavated  1400  cu.yds.  of  soft  material  in  a  10-hour  day,  while 
in  average  earth  it  excavated  1000  cu.yds.,  and  in  very  hard 
material  350'  cu.yds.  only.  Hopper  types  of  dredges  always  mean 
reduced  output,  as  the  time  is  lost  for  digging  that  is  consumed  in 
going  to  the  dump.  Inefficient  scow  service  also  means  to  decrease 
the  output  of  the  dredges.  Many  records  could  be  given  of  indi- 


66  A  TREATISE  ON  DREDGES   AND   DREDGING 

vidual  dredges,  but  a  general  idea  can  be  obtained  from  the 
following  data: 

Elevator  or  ladder  dredges  with  small  buckets,  that  is  from  4  to 
10  cu.ft.,  will  excavate  from  150  cu.yds.  of  hard  material  to  2000 
cu.yds.  of  soft  material  in  a  10-hour  day.  Working  in  average 
earth  under  ordinary  conditions  about  1000  cu.yds.  can  be  exca- 
vated. With  buckets  from  J  to  J  cu.yd.  capacity  the  output  will 
vary  from  500  cu.yds.  in  hard  material  to  3000  in  soft  mud.  In 
average  earth  from  1500  to  1800  cu.yds.  can  be  handled  in  a  10-hour 
day.  With  buckets  from  f  to  1  cu.yd.  from  1000  to  6000  cu.yds. 
can  be  excavated,  doing  in  average  earth  in  a  10-hour  day,  about 
3000  cu.yds. 

Dipper  dredges  are  seldom  made  with  buckets  of  less  than  1  cu.yd. 
capacity.  A  comparison  of  a  large  number  of  records  of  dipper 
dredges  of  various  sizes  shows  that  machines  of  this  type  working 
in  soft  mud  will  excavate  just  about  twice  as  much  as  in  hardpan 
and  such  soils.  When  logs  and  boulders  are  encountered  less  than 
this  amount  is  excavated. 

A  machine  with  a  1  cu.yd.  dipper  will  excavate  from  300  to 
800  cu.yds.,  doing  in  average  earth  about  500  cu.yds.;  with  a 
3-cu.yd.  dipper  from  1000  to  2000  cu.yds.  can  be  excavated.  In 
average  earth  about  1500  cu.yds.  with  a  6-cu.yd.  dipper  5000  cu.yds. 
of  average  earth  should  be  excavated  in  10  hours.  With  dippers 
having  a  capacity  of  from  9  to  10  cu.yds.  about  8000  cu.yds.  should 
be  excavated  in  average  earth,  in  10  hours. 

With  grapple  dredges  there  is  generally  a  less  output  than  with 
dipper  dredges,  as  they  are  generally  used  in  deeper  water,  and  then 
too  the  movement  of  the  bucket  is  slower.  With  small  buckets 
working  in  hard  material,  such  as  hardpan,  some  records  show  as 
small  an  output  as  180  cu.yds.  in  10  hours.  The  "  Fin  MacCool," 
described  later  in  this  treatise,  with  a  10-cu.yd.  clamshell  bucket 
excavating  in  deep  water,  dug  2800  cu.yds.  in  10  hours.  However, 
there  are  some  records  with  smaller  buckets  of  4000  to  5000 
cu.yds.  per  day. 

Hydraulic  suction  dredges  must  have  their  work  gauged  by  the 
size  of  the  pump,  depth  of  water,  and  length  of  discharge  pipe.  Pipes 
up  to  2000  and  3000  ft.  are  very  efficient;  over  this  distance  the 
friction  in  the  pipes  is  great,  but  many  dredges  are  designed  to-day 
to  pump  material  from  4000  to  5000  ft.  The  longest  pipe  line  known 
to  the  writer  was  2^  miles.  The  smallest  record  for  a  day's  work 


CLASSIFICATION  AND  CAPACITIES   OF  DREDGES  67 

with  a  suction  dredge  of  the  hopper  type  known 'to  the  writer  is 
250  cu.yds.  in  10  hours.  This  dredge  had  a  12-in.  pump.  Other  small 
dredges  discharging  through  pipes  show  records  of  sand  of  about 
500  cu.yds.  From  these  small  records  they  go  up  to  figures  that 
are  enormous.  The  "J.  Israel  Tarte,"  with  36-in.  pump,  averages 
from  12,000  to  20,000  cu.yds.  per  day.  The  "  Francis  T.  Simmons  " 
has  a  number  of  hourly  records  of  3000  cu.yds.  per  hour.  The 
" Atlantic  and  Manhattan,"  hydraulic  hopper  dredges  with  20-in. 
pumps,  working  in  the  Ambrose  Channel,  averaged  during  one  season 
about  9000  cu.yds.  in  24  hours  or  3700  cu.yds.  in  10  hours.  The 
"  Galveston  "  places  in  its  1400  cu.yd.  hopper  1350  cu.yds.  in  45 
minutes.  Some  records  are  much  higher  than  these.  The  largest 
dredge  in  the  world  is  the  "  Leviathan."  Working  in  the  Mersey 
River  in  England  10,000  cu.yds.  of  sand  was  excavated  in  50  minutes. 
This  was  at  the  rate  of  120,000  cu.yds.  in  a  10-hour  day.  This 
dredge  can  excavate  to  a  maximum  depth  of  70  ft, 


CHAPTER  X 
LADDER  OR  ELEVATOR  DREDGE.     GENERAL  DISCUSSION 

THE  ladder  or  elevator  dredge  consists  of  a  series  of  steel  buckets, 
attached  to  two  parallel  endless  chains  running  along  a  trussed  ladder 
and  revolving  around  two  drums  or  tumblers,  located  at  the  extrem- 
ities of  the  ladder.  The  ladder  is  kept  in  an  inclined  position,  its 
upper  end  resting  on  a  tower  mounted  on  the  boat  while  the  lower 
end  is  under  water,  raised  and  lowered  by  chains.  The  dredging 
apparatus  together  with  all  the  required  machinery  is  mounted  on 
a  vessel  which  can  be  easily  moved  from  place  to  place.  The  work 
of  the  ladder  dredge  is  easily  understood.  The  steel  buckets  forming 
an  endless  chain  in  passing  around  the  drum  at  the  lower  end  of  the 
ladder  are  brought  in  contact  with  the  soil  and  scrape  it.  The 
buckets  filled  with  the  removed  material  ascend  the  ladder  and  in 
passing  over  the  upper  tumbler  empty  their  contents  into  a  chute 
from  which  the  material  falls  into  scows  of  other  receptacles  and  is 
conveyed  to  distant  points. 

The  hull  of  the  ladder  dredge  is  made  of  different  shapes  and 
materials,  depending  upon  the  work  to  be  done.  To  insure  stability, 
it  is  desirable  to  have  the  hull  of  the  dredge  as  wide  as  possible,  and 
yet  in  the  sea-going  dredges  the  hull  should  be  made  narrow  and 
long  in  order  to  insure  seaworthy  qualities  in  the  vessel.  The  hull 
can  be  made  either  of  steel  or  wood.  In  dredges  of  small  capacity 
the  hull  is  usually  made  of  wood,  but  dredges  of  larger  capacity, 
as  for  instance  all  the  sea-going  dredges  and  also  many  of  those 
employed  in  the  harbors  or  wide  rivers,  have  the  hull  made  of  steel. 
The  advantages  derived  from  employing  steel  hulls  are:  (a)  that 
the  structure  will  be  more  solid  and  compact,  (6)  that  the  hull 
built  of  stronger  material  will  occupy  less  space  thus  leaving  more 
room  for  the  machinery,  (c)  the  vessel  will  be  of  lighter  draft 
and  will  be  very  stiff,  thus  avoiding  vibrations  that  are  always 
found  in  dredges  with  wooden  hulls  and  dangerous  on  a  machine 
mounted  on  a  float,  since  the  continuous  strong  vibrations  will  tend 
to  disconnect  the  various  parts  of  the  machinery. 

68 


LADDER  OR  ELEVATOR  DREDGE  69 


• 


When  the  ladder  is  located  on  one  side  of  the  vessel,  the  hull  is 
constructed  like  any  other  vessel,  but  when  the  ladder  is  located 
at  the  center  and  along  the  longitudinal  axis  of  the  vessel,  the  hull 
is  provided  with  a  pit  or  well.  The  dimensions  and  form  of  the  pit 
vary  with  the  work  of  the  dredge.  In  dredges  constructed  to  lower 
the  level  of  deep  channels  or  harbors,  the  ladder  working  always  at 
given  angle,  has  its  lower  end  submerged.  In  such  cases  the  pit 
is  located  amidship  and  the  hull  will  be  a  closed  one,  except  for  the 
pit.  The  ladder  can  be  located  at  the  bow  both  in  navigating  and 
dredging.  When  the  dredge  is  constructed  to  work  in  both  shallow 
and  deep  water  and  even  to  cut  its  own  channel,  the  ladder  must 
be  arranged  to  be  raised  and  lowered,  consequently  the  pit  should 
extend  through  the  stern  of  the  vessel.  In  this  arrangement  the 
hull  is  open  in  the  stern  and  a  strong  frame  or  gantry  built  on  deck 
is  used  to  connect  together  the  two  separate  walls  of  the  pit,  while 
the  ladder  is  raised  or  lowered  by  means  of  chains  and  pulleys 
attached  to  the  gantry.  In  any  case  the  pit  should  be  wide  enough 
to  permit  the  ladder  to  work  on  a  small  radius. 

The  ladder  consists  of  a  strongly  built  trussed  beam  kept  in  an 
inclined  position  and  provided  with  a  tumbler  at  each  end.  Along 
this  beam  and  around  the  drums  travel  two  endless  chains  carrying 
the  buckets.  The  upper  end  of  the  ladder  is  fixed  to  a  tower  by 
means  of  turnbuckles  which  permit  the  adjusting  of  the  chains  to 
the  required  tension.  The  lower  end  is  suspended  by  chains  passing 
over  pulleys  fixed  to  the  gantry.  Chains  attached  to  a  drum  of  a 
reversible  engine  regulate  the  raising  and  lowering  of  the  ladder. 
To  facilitate  the  running  of  the  chains  and  loaded  buckets  in  their 
ascent  along  the  ladder,  the  upper  side  of  the  trussed  beam  is  provided 
with  rollers. 

The  tumbler  or  drum  at  the  lower  end  of  the  ladder  is  meant  to 
guide  the  endless  chains  and  buckets.  These,  however,  are  moved  by 
the  driving  tumbler  located  at  the  upper  end  of  the  ladder  mounted 
on  a  tower.  Since  all  the  strain  of  dredging  apparatus  falls  upon 
the  upper  tumbler,  this  is  built  very  strong  and  it  is  usually  made  of 
cast  steel.  Its  cross-section  is  made  as  closely  as  possible  a  circle  of 
the  smallest  diameter;  but  in  order  to  smoothly  drive  the  endless 
chain  it  is  made  polygonal,  each  side  being  equal  to  the  links  of  the 
chains  and  length  of  buckets.  As  a  rule  the  driving  tumbler  is 
made  of  pentagonal  cross-section,  thus  wearing  all  the  faces  equally, 
which  would  not  be  possible  with  a  square  or  hexagonal  cross-section, 


70  A  TREATISE   ON  DREDGES  AND  DREDGING 

when  buckets  and  chains  would  always  fall  alternately  on  the  same 
faces  and  consequently  would  wear  out  unevenly.  The  lower 
tumbler  is  made  as  large  as  possible  with  a  polygonal  cross-section 
of  six  or  seven  sides. 

The  endless  chains  are  built  up  of  links  of  soft  untempered  steel; 
the  links  are  connected  together  by  cast-steel  bolts,  the  bolt  holes 
being  lined  with  soft  steel  rings  in  order  to  be  easily  renewed  when 
worn  out,  thus  preventing  the  bars  of  the  links  from  wearing. 

Steel  buckets  of  different  shapes  and  capacity  are  attached  to 
every  second  link  of  the  two  parallel  endless  chains.  The  buckets 
are  generally  made  of  two  different  shapes,  either  prismoidal  or 
as  round  as  possible.  The  lower  bucket  of  prismoidal  form  is  not  very 
satisfactory,  especially  in  clayey  soils,  when  the  material  tends  to 
adhere  to  the  corners  and  bottom;  but  the  buckets  should  not  be 
very  round  either,  since  the  lower  part  must  be  flat  in  order  to  easily 
slide  on  the  upper  side  of  the  ladder  and  revolve  smoothly  around 
the  tumblers.  All  the  buckets  are  made  of  steel,  reinforced  at  their 
cutting  edge.  Buckets  used  on  loose  soil  are  reinforced  with  a 
ring  riveted  to  the  edge  of  the  bucket,  but  those  used  in  the  excava- 
tion of  rock  or  very  hard  soil  are  reinforced  by  strong  projecting 
steel  teeth  riveted  to  the  bucket  so  as  to  be  easily  replaced  when 
worn  out.  The  capacity  of  the  buckets  working  through  loose  soil 
varies  between  J  and  1  cu.yd.,  while  that  of  the  buckets  used  on 
rock  varies  between  7  and  13  cu.ft.  To  extend  the  usefulness  of 
the  machinery  every  ladder  or  elevator  dredge  should  be  provided 
with  two  sets  of  buckets,  thus  making  the  machine  available  in 
any  material. 

The  tower  of  the  ladder  dredge  may  be  constructed  either  of 
iron  or  wood.  Dredges  with  iron  towers  are  lighter,  of  less  draft 
and  stiffer  than  those  provided  with  wooden  towers,  besides,  the 
machinery  runs  smoother  and  with  less  vibration.  Yet  man}^  dredges, 
especially  those  employed  on  narrow  rivers  and  canals,  are  even 
today  constructed  with  wooden  towers.  When  wood  is  employed  in 
the  construction  of  the  tower,  its  upper  part  is  usually  reinforced 
with  packing  pieces  at  the  points  where  shafting  causes  heavy  strains 
and  vibrations.  Yet  in  spite  of  perfect  adjustment  working  at  the 
beginning,  owing  to  the  elasticity  of  the  material  and  through 
friction,  the  joints  rack  and  the  whole  packing  becomes  loosened. 

Tower  dredges  are  classified  as  low-  and  high-tower  machines. 
The  former  are  those  with  towers  not  more  than  20  or  25  ft. 


LADDER  OR  ELEVATOR  DREDGE  71 


• 


above  deck,  while  the  latter  are  constructed  with  towers  75  and 
even  80  ft.  high.  As  a  rule,  nearly  all  the  ladder  dredges  either 
of  the  hopper  type  or  those  in  which  the  material  is  dumped  into 
scows,  have  low  towers.  High  towers  are  employed  on  dredges 
used  in  narrow  canals  and  rivers,  which  dump  the  dredged  material, 
by  gravity,  through  a  long  inclined  conveying  tube,  the  material 
being  used  for  filling  lowlands  along  the  shores  of  the  rivers  or 
forming  the  levee  or  dykes  of  canals. 

When  the  buckets,  filled  with  the  dredged  material,  reach  the 
top  of  the  ladder  and  revolve  around  the  driving  tumblers  they 
discharge  their  contents  into  a  large  box  in  communication  with 
an  inclined  chute.  Both  the  box  and  the  chute  are  covered  in  order 
to  prevent  the  material  from  splashing  on  deck.  With  low  towers, 
located  at  the  center  and  dumping  material  into  scows,  there  are 
usually  two  chutes  so  as  to  load  scows  located  on  each  side  of  the 
dredge.  By  a  system  of  chains  and  pulleys  the  chutes  may  be  called 
into  service  one  at  a  time  or  simultaneously,  at  the  will  of  the  operator. 
The  inclination  of  the  chute  depends  upon  the  quality  of  material 
to  be  dredged.  Mr.  Webster  gives  the  following  inclinations  for 
the  various  materials: 

Soft  mud 1  in  10 

Soft  clay 1  in  12  or  14 

Hard  clay 1  in  14  or  16 

Fine  sand  and  water 1  in  20  to  25 

Power  is  conveyed  to  the  driving  tumbler  by  endless  chain  and 
sprocket  wheels,  by  belt  connection  and  by  direct  action  of  the 
engine  through  a  system  of  cog  wheels.  The  method  of  turning 
the  driving  tumbler  by  an  endless  chain  and  sprocket  wheel  works 
very  well  in  loose  soils,  but  in  rock  and  hard  soils  the  sprockets  have 
a  tendency  to  break  easily.  The  method  of  transmitting  the  motive 
power  to  the  dredging  machinery  by  means  of  a  belt  connecting 
the  flywheel  of  a  horizontal  engine  with  a  system  of  cog  wheels 
acting  directly  upon  the  driving .  tumbler  works  well  in  loose  soils, 
but  in  tenacious  material  the  belt  has  a  tendency  to  slip.  This  can 
be  partially  overcome  by  an  attachment  fitted  with  a  tightener 
pulley,  which  can  increase  or  decrease  the  tension  of  the  belt.  Such 
an  arrangement  has  given  satisfactory  results  except  in  dredges 
working  through  rock.  Another  manner  of  conveying  the  power 
to  the  driving  tumbler  is  by  a  system  of  gear  wheels  acting  directly 


72  A  TREATISE  OX   DREDGES  AND   DREDGING 

from  the  pistons  of  vertical  engines.  This  method  is  commonly 
employed,  as  it  works  well  through  any  material,  and  the  speed  of 
the  motion  on  the  ladder  can  be  varied  independently  of  the  engine. 

The  efficiency  of  the  ladder  dredge  is  determined  by  the  number 
of  buckets  that  pass  over  the  driving  tumbler  every  minute,  which 
as  a  rule  varies  between  15  and  20.  But  the  efficiency  really  depends 
upon  the  material  to  be  dredged  and  the  capacity  of  buckets  em- 
ployed. Smaller  resistance  is  encountered  in  dredging  loose  soils  and 
consequently  the  driving  tumbler  may  run  at  greater  speed  and  more 
buckets  will  pass  over  it  every  minute;  yet  in  clayey  soils  it  is  neces- 
sary to  run  the  tumbler  at  reduced  speed  in  order  to  give  time  to 
the  sticky  clay  to  detach  itself  from  the  buckets.  In  removing  rock 
it  is  necessary  to  attack  the  material  with  great  force,  consequently 
the  buckets  are  run  at  high  speed,  hence  a  greater  number  will  pass 
every  minute  over  the  driving  tumbler.  However,  the  buckets, 
in  order  to  be  stronger  so  as  to  easily  break  the  rock,  will  be  of 
smaller  capacity  than  those  employed  for  dredging  loose  soils. 
Thus  the  efficiency  of  the  dredge  depends  upon  the  material  to  be 
dredged  and  the  capacity  of  the  buckets,  which,  however,  should  be 
filled  up  bnly;  to  f  of  their  capacity.  In  general,  when  the  dredge 
is  working  in  shallow  water,  the  buckets  are  traveling  at  a  slight 
inclination  only  and  consequently  the  buckets  will  be  only  par- 
tially filled,  while  they  will  be  full  when  working  in  deep  water, 
when  the  ladder  will  be  in  almost  a  vertical  position.  Consequently 
the  inclination  of  the  ladder  should  also  be  taken  into  consideration 
in  determining  the  efficiency  of  a  dredge. 

In  the  ladder  dredge  a  large  amount  of  power  is  wasted  in  over- 
coming the  great  friction  of  the  various  parts  of  the  machinery. 
Mr.  Webster,  after  an  accurate  series  of  experiments,  was  able  to 
deduce  some  practical  rule,  determining  the  power  required  to 
work  a  ladder  dredge  through  different  materials.  The  result  of 
his  experiments  are  expressed  in  the  general  formula: 


in  which  C  is  a  coefficient  varying  with  the  different  materials; 
W—  number  of  tons  per  hour  to  be  dredged; 
H=  height  of  the  upper  tumbler  from  the  bottom  of  the 
surface  ground  to  be  dredged. 

The  different  values  of  C  are  0.04  for  very  stiff  clay  and  mud, 


LADDER  OR  ELEVATOR  DREDGE  73 

0.034  for  hard  clay  and  indurated  mud  and  0.026  for  soft  mud  and 
light  sand. 

Manufacturers  have  built  a  very  large  variety  of  ladder  dredges. 
These,  however,  for  sake  of  classification,  according  to  the  locality 
in  which  they  have  to  work,  can  be  broadly  grouped  as  follows: 

1 .  Sea-going  dredges ; 

2.  Harbor  and  wide  river  dredges. 

3.  Canal  and  narrow  river  dredges. 


CHAPTER  XI 
SEA-GOING   LADDER  DREDGES 

THE  sea-going  ladder  dredges  are  those  usually  employed  to 
work  in  the  open  sea  or  for  service  in  harbors.  They  are  built  to 
sail  under  their  own  steam.  Great  care  is  necessary  in  designing 
the  hull  of  such  dredges,  as  they  should  be  even  stronger  than  the 
hull  of  ordinary  steamers,  in  order  to  insure  their  stability  against 
the  roughness  of  the  sea  and  the  strain  of  the  work.  For  these 
reasons  the  hull  of  the  sea-going  ladder  dredges  is  always  made  of 
steel,  thus  obtaining  great  stiffness  and  solidity.  The  hull  is  divided 
into  various  compartments  separated  by  water-tight  bulkheads  so 
as  to  attain  an  unsubmergible  vessel  in  case  one  of  the  compart- 
ments should  be  invaded  by  water. 

The  sea-going  ladder  dredges  are  self-propelling.  They  are 
usually  provided  with  two  ordinary  propelling  screws  located  on 
both  sides  of  the  stern  or  pit  according  to  the  type  of  the  dredge. 
Only  ladder  dredges  of  small  capacity  are  furnished  with  a  single 
propeller;  but  it  is  always  preferable  to  have  two  propellers  even 
in  the  small  dredges  of  light  draft.  The  propellers  can  be  operated 
by  separate  engines,  or  by  the  engines  of  the  dredging  machin- 
ery; in  such  a  case  a  single  device  permits  of  easily  shifting  the 
power  from  dredging  to  the  propellers  and  vice  versa. 

In  sea-going  dredges  on  account  of  stability  the  tower  is  located 
amidship  and  the  ladder  along  the  longitudinal  axis  of  the  steamer. 
When  the  dredge  is  designed  to  work  in  deep  water  the  ladder 
remains  in  a  well.  The  hull  is  closed  forward,  the  ladder  remaining 
in  tho  bow  of  the  steamer  both  in  navigation  and  in  dredging.  When 
the  dredge  is  designed  to  work  at  varying  depths,  the  ladder  must 
assume  different  inclinations  and  even  be  raised  above  the  water 
line;  the  pit  is  accordingly  open  and  located  aft.  The  boilers  and 
engines  are  located  forward.  In  such  a  case  the  bow  in  navigation 
becomes  the  stern  in  dredging. 

Sea-going  ladder  dredges  moving  continuously  from  one  place 
to  another  must  be  provided  with  commodious  quarters  for  the 

74 


SEA-GOING  LADDER  DREDGES  75 

officers  and  crew.  Should  also  have  on  board  a  well -equipped  repair 
shop,  so  as  to  repair  immediately  the  complicated  machinery  when 
out  of  order.  The  steamer  should  have  storage  for  a  supply  of 
fresh  water,  coal  and  food,  besides  the  interchangeable  parts  of 
the  various  machines. 

Sea-going  ladder  dredges  are  built  of  two  different  types,  viz., 
the  single  and  the  hopper  dredge.  The  single  sea-going  ladder 
dredges  proper  consist  of  a  strong  vessel  carrying  all  the  dredging, 
propelling,  and  other  machines  and  boilers.  The  tower  is  located 
amidship  with  a  central  chute  terminating  on  either  side  of  the  vessel 
in  order  that  the  material  may  be  easily  discharged  into  scows. 

The  hopper  dredge  is  constructed  in  a  similar  manner,  the  only 
difference  being  that  the  hull  is  much  larger  and  between  the  tower 
and  the  machinery  there  is  a  large  space  to  hold  several  hundred 
tons  of  material  which  enters  the  hopper  by  means  of  a  chute. 
The  bottom  of  the  hopper  is  provided  with  trapdoors  controlled 
by  chains  attached  and  revolving  around  two  horizontal  shafts, 
so  that  the  doors  can  be  closed  or  open  at  will.  When  the  hold  is 
filled  up  with  debris,  the  dredging  operations  are  suspended  and  the 
vessel  goes  out  to  deep  water,  where  the  doors  are  opened,  and  the 
material  will  fall  to  the  bottom  by  gravity.  Then  the  vessel  returns 
and  resumes  its  dredging  operations.  This  machine,  working  con- 
tinuously day  and  night,  is  provided  with  powerful  illuminating 
apparatus  to  make  clear  its  way. 

The  following  description  of  the  dredge  "Ville  de  Rochefort,"  . 
taken  from  Engineering,    illustrates   the    simple    sea-going   ladder 
dredge. 

In  1897  the  French  Government  intrusted  to  the  important 
firm  of  engineers  at  Lyons,  MM.  Satre,  Fils  Aine  et  Cie.,  the  con- 
struction of  a  powerful  marine  bucket  dredge,  with  twin  screws, 
intended  for  deepening  and  maintaining  the  navigation  channel 
of  the  Charente. 

This  river,  on  which  is  placed,  at  a  considerable  distance  inland, 
one  of  the  five  great  military  ports  of  France — the  port  of  Roche- 
fort — requires  to  be  considerably  deepened  to  allow  the  passage 
of  fully  equipped  ironclads  between  Rochefort  and  the  sea. 

Not  only  is  there  a  rocky  bar  at  one  point,  but  vast  quantities 
of  mud  are  constantly  being  deposited  on  the  river  bed,  seriously 
reducing  the  available  depth  of  water. 

For  this  reason  the  French  Admiralty  considered  it  necessary 


SEA-GOING  LADDER  DREDGES  77 

• 

to  have  at  its  disposition  a  dredging  machine  sufficiently  powerful 
to  maintain  the  navigable  channel  open  at  all  times. 

This  machine  has  recently  been  delivered  by  the  constructors 
at  the  port  of  Rochefort  after  a  series  of  interesting  trials,  to  which 
reference  will  be  made  later. 

The  general  view  of  the  dredge  is  given  in  Figs.  15  and  16. 

It  is  provided  with  a  single  inclined  central  ladder,  and  is  fitted 
with  two  screws. 

The  engines  are  of  sufficient  power  to  give  a  speed  to  the  vessel, 
when  loaded,  of  6  knots,  and  to  insure  an  efficiency,  under  unfavor- 
able conditions  of  weather,  of  a  minimum  of  330  cu.yds.  of  compact 
mud  such  as  forms  the  bottom  of  the  River  Charente,  at  a  depth  of 
33  ft.  below  the  surface. 

The  hull  is  constructed  with  an  open  end  to  provide  a  passage 
for  the  ladder,  and  to  allow  the  dredge,  in  case  of  necessity,  to  make 
its  own  channel  as  it  advances ;  the  position  of  the  ladder  can  be 
shifted  in  such  a  way  as  to  .excavate  against  fixed  works  (such  as 
quay  walls)  13  ft.  in  advance  of  the  hull,  in  slight  depths. 

The  material  raised  is  discharged  through  two  side  passages 
on  either  side  of  the  vessel. 

The  hull,  which  is  built  entirely  of  steel,  has  the  following 
principal  dimensions: 

Ft.         In. 

Length  on  deck 144        6 

Width 32         9 

Depth 11         2 

The  hull  is  divided  into  nine  compartments  by  eight  watertight 
bulkheads. 

The  internal  fittings  of  the  vessel  for  the  officers  and  crew  are 
very  complete;  they  comprise  a  cabin  for  the  engineer  in  charge, 
which  also  serves  as  the  watchroom,  placed  on  the  upper  deck;  the 
captain's  cabin  is  on  the  main  deck;  beneath  the  upper  deck  is  a 
large  messroom  for  the  officers;  and  on  each  side  is  arranged  the 
accommodation  for  the  engineers,  the  dredging  staff,  and  the  crew. 

The  propelling  machinery  consists  of  two  compound  surface- 
condensing  engines  of  the  steam-hammer  type,  capable  of  developing 
together  500  horse-power. 

These  engines  are  arranged  either  to  drive  the  scows  or  the 
dredging  machinery,  a  simple  and  quick-acting  system  of  clutches 
being  provided  to  make  the  connections  with  one  or  the  other. 


78  A  TREATISE  ON  DREDGES  AND   DREDGING 

The  dredging  machinery  is  driven  by  gearing  through  a  brake 
transmission  to  avoid  the  danger  of  fracturing  any  part  of  the 
machinery  in  the  event  of  a  sudden  shock  arising  from  contact  with 
unusually  hard  material. 

The  engines  are  arranged  to  be  driven  together  or  separately, 
so  that  the  power  of  one  or  both  can  be  applied  to  the  screws  or 
to  the  dredging  machinery. 

The  principal  dimensions  of  the  engines  are  as  follows: 

Inches. 

Diameter  of  high-pressure  cylinders 20 . 08 

Diameter  of  low-pressure  cylinders 34 .26 

Length  of  stroke 19 . 69 

Each  engine  is  provided  with  a  separate  starting  gear  driven 
by  a  special  motor,  so  that  the  engines  can  be  turned  at  slow  speeds 
down  to  two  revolutions  a  minute,  to  facilitate  the  operations  of 
mounting  or  dismounting  the  bucket  chain. 

The  boilers,  two  in  number,  are  of  the  ordinary  marine  type, 
registered  to  a  working  pressure  of  114  Ib.  per  sq.in.,  and  of  ample 
capacity  to  drive  the  main  and  all  the  auxiliary  machinery. 

The  gearing  which  transmits  the  motion  from  the  engine  to  the 
bucket  shaft  is  so  arranged  that  its  speed  can  be  varied  independently 
of  that  of  the  engine. 

This  arrangement  is  desirable  in  consequence  of  the  variable 
nature  of  the  material  which  has  to  be  lifted. 

The  bucket  ladder  is  central  and  is  placed  in  the  middle  of  the 
hull;  it  is  so  hung  that  the  bucket  wheel  at  the  lower  end  can  be 
raised  clear  of  the  water  when  the  vessel  is  being  propelled;  its 
length  is  sufficient  to  dredge  at  a  depth  of  33  ft.  below  the  surface. 

It  is  mounted  in  such  a  manner  that  it  can  be  easily  shifted  aft, 
when  it  is  desired  to  remove  the  mud  lying  against  the  foot  of  quay 
walls  in  a  slight  depth  of  water. 

The  bucket  chain  is  made  of  links  of  soft  untempered  steel 
connected  by  cast-steel  bolts;  the  bolt  holes  are  lined  with  soft 
steel  rings  which  can  be  easily  renewed  when  worn. 

The  buckets  are  made  entirely  of  steel  with  a  reinforced  cutting 
edge;  their  capacity  is  about  1  cu.yd.,  they  can  be  driven  at  speeds 
varying  from  10  to  16  buckets  past  the  discharge  channels  per 
minute,  according  to  the  nature  of  the  ground  being  excavated. 

The  winches  for  lifting  the  ladder  are  driven  by  a  separate 
compound  engine  of  sufficient  power  to  raise  the  ladder  when  the 


SEA-GOING  LADDER  DREDGES  79 

buckets  are  all  loaded.  The  dredge  is  lighted  throu^iout  electrically; 
internally  by  incandescent  lamps,  and  on  deck  by  arc  lamps;  current 
is  furnished  by  a  Laval  electro-turbine  plant. 

With  regard  to  the  trials  made  with  this  dredge,  we  cannot  do 
better  than  reproduce  a  part  of  the  official  reports  of  the  Commis- 
sion nominated  by  the  Minister  of  Marine:  "The  trials  provided 
for  by  the  terms  of  the  contract  were  carried  out  on  June  18  last, 
at  the  same  time  the  machinery  was  tested  for  the  consumption  of 
fuel. 

"The  speed  obtained  was  6.053  knots;  the  consumption  of  fuel 
contracted  for  was  2.09'  lb.,  but  the  tests  showed  a  consumption 
of  1.97  lb.  per  horse-power  per  hour. 

"The  trials  were  continued  for  six  consecutive  hours,  during 
which  the  working  was  extremely  satisfactory. 

"  The  tests  for  dredging  efficiency  were  made  with  material  similar 
to  that  found  in  the  bed  of  the  Charente ;  the  Commission  continued 
these  tests  for  60  hours  consecutively. 

"  It  reported  that  the  dredge  worked  with  one  engine  and  one 
boiler,  and  that,  at  the  minimum  speed  of  ten  buckets  per  minute, 
it  gave  an  average  efficiency  of  485  cu.yds.  an  hour;  this  amount 
included  the  time  necessary  for  operating  the  discharge  channels, 
and  stopping  and  starting  the  machinery;  without  including  these 
delays,  the  amount  raised  was  6536  cu.yds. 

"  From  the  foregoing  it  will  be  seen  that  the  efficiency  is  largely 
in  excess  of  the  .terms  of  the  contract,  which  prescribed  a  total  of 
333  cu.yds.  per  hour. 

"The  consumption  of  fuel  measured  direct  under  the  most  unfavor- 
able conditions,  averaged  102.76  Ibs.  per  loaded  barge,  equivalent 
to  1.08  Ibs.  per  cu.yd.  lifted. 

"By  the  terms  of  the  contract  1.53  lb.  of  fuel  per  cu.yd.  were 
allowed,  so  that  in  all  respects  the  results  were  highly  satisfactory." 

The  Commission  reported  in  an  equally  favorable  manner  on 
the  electric  installation. 

The  following  description  of  the  Pas-de-Calais  dredges,  translated 
from  the  Genie  Civile,  serves  to  illustrate  a  ladder  dredge  of  the 
hopper  type. 

The  hopper  ladder  dredge  "Pas-de-Calais/'  see  Fig.  17,  was  built 
by  the  Henry  Satre  Fils  Aine  et  Cie.  for  the  French  Government  for 
the  use  of  several  harbors  along  the  English  Channel,  but  mainly 
for  the  Naval  Station  of  Boulogne.  In  order  that  the  dredging 


80 


A  TREATISE  ON  DREDGES   AND   DREDGING 


operations  and  especially  the  continuous  movements  of  tugboats 
and  scows  in  the  service  of  the  dredge  would  not  interfere  with 
traffic  through  the  narrow  channel,  and  also  on  account  of  the  heavy 
seas  prevailing  in  the  locality,  it  was  decided  to  build  this  ladder 
dredge  with  a  large  hopper  to  receive  the  debris.  The  hopper  loaded, 
the  steamer  would  go  out  to  unload  its  cargo  into  deep  water  and 
return  to  resume  its  dredging  operations. 


FIG.  17.— Dredge  "Pas-de-Calais." 
The  principal  dimensions  of  the  steamer  are : 

Ft.          In. 

Length 180       3£ 

Width 32       7 

Depth 14        6 

The  motive  power  is  provided  by  two  independent  compound 
engines  with  three  cylinders  each,  developing  together  650  H.P. 
The  engines  are  furnished  with  a  regulator,  by  means  of  which  it 
is  possible  to  regulate  the  speed  of  the  buckets  according  to  the 
resistance  of  the  soil  encountered  in  dredging. 

Steam  is  generated  by  two  tubular  boilers  of  marine  type  and 
so  arranged  that  they  can  work  either  together  or  separately  and 


SEA-GOING  LADDER   DREDGES  81 

supply  either  one  of  the  engines  or  both.    The  grate  i^of  an  improved 
type,  which  permits  fuel  of  every  description  to  be  burnt. 

The  turning  of  the  upper  tumbler  commanding  the  bucket 
chain  in  by  a  system  of  shafts  and  cogwheels.  A  friction  clutch, 
easily  handled,  is  attached  to  the  upper  tumbler"  in  order  to 
prevent  any  break  in  the  various  parts  of  the  machinery  in  case 
very  hard  rock  or  other  serious  obstacles  are  encountered. 

The  dredge  is  provided  with  two  sets  of  buckets;  those  to  be 
used  is  loose  soils  or  in  soils  of  the  average  consistency  have  a  capacity 
of  21.5  cu.ft.  each;  while  those  designed  to  work  in  soils  of  greater 
resistance,  as  conglomerates,  ledges  of  rock,  etc.,  are  of  12.4  cu.ft. 
capacity  and  are  strongly  reinforced  with  steel  teeth,  which  are  fixed 
to  the  buckets  in  a  very  simple  manner,  so  as  to  be  easily  changed 
when  worn  out. 

Starting  gears  allow  the  engines  to  be  turned  at  a  very  slow  speed 
in  order  to  facilitate  the  mounting  or  dismounting  of  the  buckets. 

The  hopper  is  located  amidship  and  has  a  capacity  of  700  tons. 
The  hopper  is  filled  through  a  central  chute.  There  are  also  two 
lateral  chutes  in  order  that  the  debris  may  be  dumped  on  scows 
placed  alongside. 

The  bottom  of  the  hopper  is  formed  by  12  gates  made  of  wood 
lined  with  sheet  iron.  Each  pair  of  gates  is  controlled  by  6  chains 
wound  around  a  horizontal  axis.  After  the  material  in  the  hopper 
has  been  dumped  the  gates  are  closed  again  by  means  of  a  special 
engine  acting  directly  upon  the  horizontal  axis  commanding  the 
chains. 

The  bucket  ladder  is  arranged  to  work  at  different  depths,  varying 
from  10  to  40  ft.  The  special  construction  of  the  hull  allows  the 
bucket  ladder  to  move  in  a  parallel  direction  and  also  to  be  raised 
and  -lowered.  On  account  of  such  an  arrangement  the  dredge  may 
cut  its  own  way  and  also  dredge  against  the  bottom  of  quay  walls. 

On  the  back  of  the  ladder  there  is  a  pentagonal  wheel  for  the 
support  and  guide  of  the  bucket  chain.  Such  an  arrangement  has 
the  advantage  of  allowing  the  ladder  to  work  in  a  more  vertical 
position  and  to  shorten  at  the  same  time  the  length  of  the  bucket 
chain.  Besides,  the  bucket  chain  resting  on  this  wheel  will  run 
more  smoothly  than  before,  thus  avoiding  shocks  and  much  wear. 

The  journals  of  the  axles  of  the  upper  tumbler  of  the  ladder  are 
provided  with  Belleville  springs,  absorbing  the  shock  produced 
by  the  buckets  encountering  some  extraordinary  obstacle.  Owing 


82  A  TREATISE  ON   DREDGES  AND   DREDGING 

to  the  elasticity  of  the  upper  portion  of  the  ladder,  many  breaks 
are  certainly  spared  to  the  dredging  machines. 

All  the  winches  are  moved  by  independent  double  cylinder 
engines;  the  winch  controlling  the  ladder  is  provided  with  friction 
clutches  of  Minoto's  system  and  also  with  a  friction  brake  applied 
by  means  of  a  lever  arm.  The  lowering  or  raising  of  the  ladder  is 
done  by  means  of  lever  arms  controlling  the  drums  of  the  winch 
around  which  the  chains  holding  the  lower  end  of  the  ladder  are 
played  in  or  out. 

A  steam  crane  is  ocated  at  the  bow  of  the  steamer  for  lifting 
the  rocks  too  large  to  be  taken  up  by  the  buckets;  while  a  second 
steam  crane  is  mounted  on  deck  for  the  raising  or  lowering  of 
the  ladder.  Both  cranes  are  provided  with  friction  clutches  of 
Minoto's  system. 

The  motive  power,  as  indicated  above,  is  provided  by  two  inde- 
pendent engines.  These  are  so  arranged  that  each  one  of  them  may 
act  either  on  the  propelling  or  dredging  apparatus.  The  advantage 
of  such  an  arrangement  is  that  in  case  one  of  the  engines  breaks  down 
the  work  will  continue  without  interruption.  Besides,  these  two 
engines  can  be  easily  coupled  so  as  to  act  directly  on  the  dredging 
apparatus  when  working  in  hard  material.  On  the  dredge  there 
are  two  propellers,  four  bladed,  with  their  shafts  in  continuation  of 
the  revolving  shafts  operated  by  the  engine.  The  great  advantage 
of  two  propellers  is  that  the  vessel  may  turn  in  a  small  radius 
when  the  two  propellers  are  revolving  in  opposite  directions. 
A  simple  movement  allows  the  power  to  be  changed  from  dredging 
to  the  propellers. 

On  account  of  the  heavy  seas  prevailing  in  the  locality  the  dredge 
was  made  a  real  steamer.  Sailing  under  her  own  steam  she  went 
alone  from  Marseilles  to  Boulogne  and  on  such  a  long  voyage  she 
proved  her  seaworthy  qualities.  The  hull  is  entirely  of  steel  divided 
in  various  compartments  separated  by  watertight  bulkheads  to 
insure  its  floating  even  in  case  one  of  the  compartments  were 
injured. 

The  dredge  is  equipped  with  every  device  ordinarily  found  on  a 
modem  steamer. 

The  messroom  and  quarters  for  the  officers  and  crew  and  the 
cabins  of  the  engineers  and  captain  are  well  heated  and  ventilated 
and  are  lighted  by  electricity.  Powerful  arc  light  lamps  mounted 
on  deck  furnish  light  for  work  at  night. 


CHAPTER  XII 


SEMI-SEA-GOING  STATIONARY  AND   HIGH-TOWER  LADDER 

DREDGES 

THE  ladder  dredges  designed  to  work  on  rivers,  canals,  or  within 
well  protected  harbors  are  built  of  different  types.  For  sake  of 
classification  these  various  dredges  can  be  grouped  in  semi-sea-going, 


FIG.  18.— Dredge  "  Cadiz." 

which  are  provided  with  self-propelling  apparatus,  when  stationary, 
not  equipped  with  propelling  machinery,  and  must  be  towed  from 
place  to  place,  and  again  we  have  the  high-  and  low-tower  types. 

Semi-sea-going  ladder  dredges  have  the  hull  so  constructed  as 
to  insure  stability  and  steadiness  to  the  machinery  under  the  great 
strain  of  the  work  rather  than  to  give  seaworthy  qualities  to  the 
steamer.  The  ratio  between  the  length  and  width  of  the  hull  of 
these  dredges  is  smaller  than  in  those  of  the  sea-going  type.  To 
allow  the  machine  to  work  at  various  depths  and  consequently 
with  the  ladder  at  different  inclinations  the  hull  is  always  open 
and  the  walls  of  the  pit  are  strengthened  by  a  solid  structure  above 
deck.  The  ladder  well  can  be  located  at  the  bow  of  the  steamer  and 
then  the  boilers  and  engines  are  aft,  or  vice  versa. 

83 


84 


A  TREATISE   ON  DREDGES  AND   DREDGING 


With  semi-sea-going  dredges,  navigating  in  waters  which  are 
usually  quiet  and  calm,  the  propelling  apparatus  is  of  secondary 
importance.  This  consists  of  a  single  screw  located  at  the  stern  in  the 
ladder  pit,  when  the  stern  in  navigation  becomes  the  bow  in  dredging. 
Fig.  18  shows  the  semi -sea-going  ladder  dredge  "  Cadiz  "  built  by 
the  H.  Satre  Fils  Aine  et  Cie.  for  the  harbor  of  Cadiz,  Spain,  in  which 
the  propeller  is  located  in  the  pit.  The  propelling  apparatus  may 
consist  also  of  a  single  paddle-wheel  located  in  the  ladder  pit. 

It  is  not  possible  to  use  two  side  wheels  on  account  of  the  chutes 
for  the  dredged  materials.  In  such  a  case  the  walls  of  the  pit  are 
greatly  extended  as  indicated  in  Fig.  19,  which  represents  one  of 
these  dredges  built  by  the  H.  Satre  et  Cie.  and  used  in  the  canal 
between  the  Marne  and  Rhine  rivers.  The  propelling  apparatus 
may  consist  also  of  a  sprocket  wheel  of  large  dimensions  located 
at  the  stern.  In  revolving,  the  wheel  will  engage  continuously 
the  bed  of  the  river,  thus  causing  the  forward  motion  of  the  dredge. 


FIG.  19. — Dredge  for  the  Marne  Canal. 

This  method  of  propulsion  was  ordered  by  the  Department  of  Fonts 
at  Chausse'cs  in  France  for  dredges  to  be  used  in  the  improvement 
of  the  Rhone  River,  one  of  which  is  shown  in  Fig.  20. 


STATIONARY  AND   HIGH-TOWER  LADDER  DREDGES 


85 


Stationary  ladder  dredges  are  those  without  propelling  apparatus. 
They  are  towed  from  place  to  place  and  the  small  movement  required 
to  follow  the  progress  of  the  work  is  obtained  by  paying  in  and  out 
the  various  ropes  attached  to  the  four  corners  of  the  boat  and  moored 
to  distant  points.  Stationary  ladder  dredges  of  American  construc- 
tion are  usually  provided  with  three  or  four  spuds  so  arranged  that 


FIG.  20. — Dredge  on  the  Rhone  River  Propelled  by  Sprocket  Wheel. 

when  lowered  the  dredge  will  remain  strongly  fixed  to  the  bottom. 
An  advantage  derived  from  using  spuds  consists  in  obtaining  a 
machine  that  can  be  swung  around  one  spud  as  center  of  rotation, 
thus  dredging  in  great  arcs  or  circles. 

The  hull  of  the  stationary  ladder  dredge  can  be  made  of  any 
shape,  but  as  a  rule  it  is  made  with  a  flat  bottom  like  any  ordinary 
float.  The  hull,  however,  is  provided  with  the  ladder  pit,  tower, 
bucket  chain,  boiler  and  engines  similar  to  those  used  in  the  sea-going 
and  semi-sea-going  ladder  dredges,  with  the  only  difference  that  all 
the  machines  are  mounted  on  deck.  Accommodations  are  not  pro- 
vided for  officers  and  crew,  as  the  men  remain  on  board  only 
during  the  working  hours.  The  vessel  is,  as  a  rule,  of  very  light 
draft  and  able  to  navigate  and  operate  in  very  shallow  waters. 

Fig.  21  shows  an  ordinary  stationary  ladder  dredge  built  by 
A.  F.  Smulders  of  Schiedam,  Holland. 


86  A  TREATISE   ON  DREDGING   AND  DREDGES 

Following  is  the  description  of  a  stationary  ladder  dredge  of 
American  construction,  a  striking  feature  being  that  the  excavated 
materials  are  conveyed  to  the  shore  by  means  of  an  endless  belt 
conveyor.  This  machine  was  used  on  Fox  River,  Wis.  and  was 
described  by  Mr.  L.  M.  Mann,  the  engineer  in  charge,  in  the 
Engineering  News,  October  25,  1906. 

The  plant  as  illustrated  in  Figs.  22  and  23  consists  of  a  dredge 
with  two  intermediate  and  one  delivering  scow.  The  dredge  is  a 
regular  elevator  or  chain-bucket  dredge,  having  a  chain  of  39 


FIG.  21. — Stationary  Ladder  Dredge. 

buckets  of  5  cu.ft.  capacity  each  rolling  over  a  steel  ladder.  These 
buckets  are  provided  with  steel  teeth  for  cutting  up  clay  and  digging 
the  hardest  material,  and  may  be  set  to  dig  at  any  desired  depth  up 
to  10  ft.  The  dredge  swings  on  a  stern  spud  amidship,  allowing 
it  to  dig  on  a  circle  of  about  80  ft.  radius,  covering  a  width  of  channel 
of  about  145  ft. 

The  material,  on  leaving  the  elevator  buckets  at  the  top  of  the 
ladder,  is  deposited  in  a  hopper  and  passes  thence  onto  a  belt  con- 
veyor which  conveys  it  aft  over  the  stern  of  the  dredge  and  delivers 
it  into  another  hopper  in  the  forward  end  of  the  intermediate  or 
delivery  scow.  These  several  scows  are  provided  with  belt  con- 
veyors which  keep  the  material  in  continuous  motion  until  it  is 
finally  deposited  where  desired,  either  on  shore  or  in  a  dump 
scow.  The  conveyor  on  this  scow  projects  by  means  of  a  steel 
ladder  over  the  stern  a  distance  of  40  ft.,  and  is  hung  from  a 


88       A  TREATISE  ON  DREDGES  AND  DREDGING 

gantry,  permitting  it  to  be  raised  to  20  ft.  above  water  or  adjusted 
to  any  lower  elevation.  The  latter  scow  may  be  swung  at  any  angle 
to  deposit  the  debris  on  either  side  of  the  river  without  disturbing 
the  rest  of  the  plant;  or  it  may  be  attached  directly  to  the  dredge 
and  used  without  the  intermediate  scows,  which  at  first  seemed  a 
difficult  problem  to  solve.  The  complete  plant  carries  the  spoil 
300  ft.  from  the  point  of  digging,  and  this  distance  is  limited  only 
by  the  number  and  length  of  the  conveyors  used.  The  conveyors 
are  of  the  Ridgway  type,  but  are  protected  on  the  sides  and  bottom 
to  prevent  spilling;  the  belt  is  rubber,  32  in.  wide,  and  will  easily 
convey  the  full  delivery  of  the  dredge. 


FIG.  23.— Dredging  Plant  Used  on  the  Fox  River,  Wis. 

The  bucket  chain  of  the  dredge  is  driven  by  a  9X12  in.  double 
reversing  engine  through  gearing  which  also  operates  the  ladder- 
hoist  drum.  A  six-drum  winch,  driven  by  a  6X6  in.  double  engine, 
is  also  provided  for  operating  anchor,  spud  lines,  etc.  A  walking 
spud,  operated  by  a  steam  cylinder,  is  provided  to  move  the  dredge 
forward.  The  belt  conveyors  on  the  dredge  and  scows  are  operated 
by  electric  motors  supplied  by  a  35-KW.  electric  generator  on  the 
dredge  directly  connected  with  a  10  X 10  in.  engine,  which  also  furnishes 
electric  lights  for  the  plant  and  power  for  operating  a  6-in.  spray 
pump  for  cleaning  the  belts.  Steam  is  furnished  by  a  Scotch  marine 
boiler  9  ft.  diameter,  10  ft.  long,  water-back  type,  with  two  Adamson 
furnaces  35  in.  in  diameter. 

The  delivery  scow  is  provided  with  a  winch  operated  by  an 
electric  motor,  for  handling  the  anchor  lines,  gantry  and  spud. 


STATIONARY  AND  HIGH-TOWER  LADDER  DREDGES          89 

Quarters  for  the  crew  are  provided  on  the  upp^r  deck  and  are 
unusually  spacious,  light  and  well  ventilated. 

The  hulls  are  built  entirely  of  Oregon  fir,  the  dredge  hull  being 
75  ft.  long,  31  ft.  beam  and  6  ft.  depth  of  hold.  The  intermediate 
scows  are  40  ft.  long,  16  ft.  wide  and  3  ft.  depth  of  hold,  each  carrying 
belt  conveyors  65  ft.  long.  The  delivery  scow  is  nearly  triangular 
in  shape,  being  31  ft.  4  in.  long,  16  ft.  4  in.  wide  and  2  ft.  deep  at 
the  forward  or  receiving  end  and  33  ft.  4  in.  wide  and  4  ft.  deep  at 
the  after  delivery  end.  The  hull  is  given  this  unusual  shape  the 
better  to  support  the  overhanging  load  of  the  delivery  conveyor, 
and  to  secure  a  greater  angle  of  gyration  when  the  scow  is  attached 
to  the  dredge.  The  width  of  the  hull  was  limited  to  allow  it  to  pass 
the  locks,  which  are  only  35  ft.  wide. 

The  contract  stipulated  that  the  dredge  should  have  a  capacity 
of  250  cu.yds.  per  hour  in  ordinary  digging.  The  first  preliminary 
test  demonstrated  that  she  could  dig  400  cu.yds.  per  hour;  and 
she  actually  did  dig  200  yds.  in  the  toughest  kind  of  clay  and  hardpan 
under  adverse  conditions.  Although  at  times  the  buckets,  when 
not  full,  carry  considerable  water,  this  flows  back  from  the  conveyors 
into  the  river  and  the  spoil  is  deposited  quite  free  from  water.  The 
crew  of  the  plant  now  consists  of  9  men,  but  can  probably  be  reduced 
eventually.  The  cost  of  operation,  including  fuel,  is  about  $30  per 
day,  but  the  plant  will  undoubledly  reduce  the  actual  cost  of  dredging 
over  the  old  dipper  dredge  50  per  cent  or  more.  The  cost  of  wear 
and  tear  cannot  be  determined,  of  course,  until  the  dredge  has  been 
operated  about  two  seasons.  The  principal  wear  and  cost,  no  doubt, 
will  be  the  rubber  conveyor  belts;  but  this  will  be  minimized  by 
the  comparatively  small  repairs  to  the  machinery  as  compared  with 
a  dipper  dredge. 

One  of  the  most  difficult  conditions  in  the  operation  of  this 
plant  is  the  varying  load,  due  not  only  to  the  varying  depths  of 
water  in  front  of  the  dredge  or  the  varying  face  of  the  cut,  but  the 
character  of  the  material.  Each  requires  a  different  adjustment  of 
the  machinery,  that  is,  a  different  speed  of  bucket  chain  and  con- 
veyors. This  may  vary  in  a  single  turn  of  the  dredge,  as  sand,  clay, 
hardpan,  or  a  mixture  of  these  each  act  very  differently.  When  a 
uniform  load  of  gravel  or  sand  is  to  be  moved,  the  operation  is  much 
simplified. 

High-tower  Dredges.  When  the  dredged  materials  are  used 
for  forming  ditches  or  filling  lowlands  along  the  shore,  the  ladder 


90  A  TREATISE  ON  DREDGES  AND  DREDGING 

dredges  are  built  with  high  towers.  The  materials  are  then  conveyed 
to  the  dumping  place  by  means  of  a  long  tube  and  they  are  discharged 
by  gravity.  The  height  of  the  tower  depends  upon  two  factors,  viz., 
the  distance  of  the  dump  and  the  elevation  of  the  shores  from  deck. 
They  are  built  of  different  heights,  but  always  between  50  and  80 
ft.  The  ladder  is.  always  located  at  the  middle  of  the  boat  in  an 
open  pit. 

When  the  buckets  have  reached  the  top  of  the  ladder,  wrhile 
they  revolve  around  the  upper  tumbler  the  materials  fall  into  a  bell 
leading  to  a  closed  chute,  which  is  extended  into  a  long  tube.  With 
dredges  built  to  work  in  narrow  rivers  or  canals,  when  both  shores 
can  be  easily  reached  by  the  conveying  apparatus,  they  are  usually 
provided  with  two  chutes  and  two  tubes.  In  this  manner  were  con- 
structed the  high-tower  ladder  dredges  used  on  the  Panama  Ganal 
under  the  French  and  also  on  the  Nicaragua  Canal.  The  conveying 
tubes  are  made  of  sheet  iron  2  or  3  ft.  in  diameter.  In  dredges  provided 
with  only  one  long  discharging  tube  this  is  located  on  one  side  of  the 
boat  at  a  right  angle  to  the  ladder.  The  tube  is  supported  from  the 
tower  by  a  series  of  gang  wire  ropes  and  also  from  a  trussed  A  frame 
located  on  one  side  of  the  boat  and  strongly  fixed  to  the  other  side 
by  means  of  backstays.  The  conveying  tube  is  made  of  varying 
lengths,  reaching  sometimes  150  and  even  180  ft.  To  reach  points 
at  great  distances  from  the  dredge  the  conveying  tube  is 
extended  to  land,  but  in  such  a  case  the  land  section  of  the  tube 
is  supported  by  specially  constructed  trusses.  To  facilitate  the  flow 
of  the  materials  through  the  tube  this  is  placed  with  an  inclination 
varying  from  2  to  10  per  cent,  depending  upon  the  quality  of  the 
dredged  materials.  The  descent  of  the  materials  through  the  tube 
is  facilitated  also  by  means  of  water  jets  forced  by  a  centrifugal 
pump  placed  on  deck,  which  continuously  flush  the  tube. 

The  high-tower  ladder  dredge  presents  several  disadvantages: 
1st,  the  necessity  of  elevating  the  materials  to  a  greater  height  than 
absolutely  necessary,  and  consequently  the  motive  power  is  not 
economically  utilized;  2d,  the  necessity  of  acquiring  powerful 
and  expensive  machines,  which  involve  high  running  expenses; 
3d,  the  stability  of  the  dredge  is  greatly  hampered  on  account  of 
having  very  high  towers  on  boats  usually  built  of  small  dimensions; 
4th,  the  material  being  deposited  in  a  fluid  state  and  near  the 
edge  of  water  has  a  tendency  to  run  back  again  to  the  point  of 
excavation. 


STATIONARY  AND  HIGH-TOWER  LADDER  DREDGES          91 

Many  engineers  object  to  this  type  of  dredge/ while  there  are 
others  who  absolutely  condemn  it  as  obsolete.  But  when  it  is 
considered  that  in  the  ladder  dredges,  the  coal  consumption  repre- 
sents only  10  or  15  per  cent  of  the  running  expenses,  it  is  easily 
realized  that  the  cost  per  unit  of  volume  of  the  dredged  materials 
will  not  be  greatly  affected  by  even  doubling  the  cost  of  fuel.  On 
the  other  hand  the  great  advantage  of  these  machines  consists  in 
the  fact  that  they  convey  the  dredged  materials  to  the  dumping 
place  without  additional  cost  of  transportation.  Consequently 
the  small  increase  in  the  cost  of  dredging  is  more  than  compensated 
by  the  free  conveyance  of  the  debris  to  the  dumping  places.  Another 
advantage  of  the  high-tower  ladder  dredge  consists  in  the  fact  that 
working  day  and  night  it  will  perform  the  work  of  two  machines, 


FIG.  24. — High  Tower  Ladder  Dredge  "City  of  Paris." 

thus  greatly  reducing  the  cost  of  the  plant  and  the  general  expenses. 
Even  to-day  these  high-tower  ladder  dredges  in  some  classes  of  work 
will  give  the  same  satisfactory  results  as  they  did  along  the  Suez 
Canal  in  the  early  days  of  their  existence.  Over  one-third  of  the 
Suez  Canal  was  excavated  by  means  of  these  high-tower  ladder 
dredges,  and  they  were  found  very  efficient  in  dredging  the  lower 
sections  of  the  Panama  Canal  during  the  French  Administration. 

The  following  description  of  the  dredge  "  City  of  Paris  "  taken 
from  the  Scientific  American,  serves  to  illustrate  a  high-tower  ladder 
dredge  built  in  the  United  States,  and  used  by  the  American  Contract- 
ing &  Dredging  Co.  of  New  York  for  the  Panama  and  Nicaragua 
Canals.  Shown  in  Fig.  24. 

The  typical  American  dredge,  represented  by  the  "  City  of  Paris/' 
is  provided  with  composite  hull  115  ft.  long  and  56  ft.  wide.  In 


92  A  TREATISE   ON  DREDGES   AND   DREDGING 

the  forward  end  of  the  dredge  is  a  slot,  through  which  the  lower 
section  of  the  ladder,  36  ft.  long  and  7  ft.  wide,  descends.  An  endless 
chain  of  buckets  travels  up  and  down  the  ladder,  cutting  away 
the  bottom  wherever  directed,  and  delivering  the  material  to  the 
discharger  on  top  of  the  tower.  The  upper  section  of  the  ladder 
for  this  purpose  is  carried  up  to  the  top  on  an  incline.  A  joint  is 
provided  between  the  sections,  so  that  the  lower  portion  can  be 
raised  and  lowered.  The  upper  section  is  73  ft.  10  in.  long.  The 
buckets  are  of  f-in.  steel,  and  have  a  capacity  of  1  cu.m.  each. 
The  links  of  the  chain  are  If  in.  x  1  in.  steel,  and  are  3  ft.  long. 
The  shaft  at  the  top  of  the  tower,  around  which  the  chain  and  buckets 
travel,  is  14  in.  in  diameter. 

The  chain  is  driven  by  double-cylinder  engines,  16x24  in., 
with  10-ft.  driving  pulley  with  38-in.  face.  The  dredge  is  anchored 
by  wooden  spuds  or  heavy  vertical  beams,  25  in.  diameter,  with 
1800  Ib.  iron  shoes  upon  their  lower  ends.  These  ends  are  lowered 
to  the  bottom,  and  sinking  through  the  earth  anchor  the  machine 
securely.  Besides  the  main  engine,  there  are  several  auxiliary 
engines  for  working  the  spuds,  raising  the  ladder,  etc. 

The  material  as  dredged  and  raised  to  the  top  of  the  tower  is 
emptied  into  the  bell  of  one  of  a  pair  of  iron  chutes.  These  are  pipes 
3  ft.  in  diameter  and  185  ft.  long,  which  run  far  out  on  both  sides 
of  the  tower.  Water  is  pumped  into  them  along  with  the  solid 
material.  Great  banks  of  sand  are  built  up  by  its  operations. 

When  Mr.  W.  P.  Williams,  Sr.,  examined  this  dredge  in  the 
Panama  Canal  in  1889  under  the  French  Administration,  it  was 
running  nineteen  to  twenty-one  buckets  per  minute,  three-fourths 
full,  three  buckets  to  the  cu.m.  The  expansion  of  material  in  buckets 
was  30  per  cent,  occupying  more  volume  in  the  buckets  than  in 
bank.  He  estimated  in  twenty-four  hours'  work  it  would  accomplish 
4800  cu.m. 

He  gives  the  average  efficiency  of  this  machine  as  follows: 

Soft   sticky  clay  buckets  not   fully  emptying    at 

upper  tumbler 3000  to  4000  cu.yds.  per  day 

Hard  clay 4000 

Sand 5000 

The  machine  is  under  the  complete  control  of  the  captain,  who 
is  stationed  on  the  bow  of  the  machine.  A  system  of  wheels  at  his 
hand  connects  with  the  different  engines,  namely,  raising  and  lower- 


STATIONARY  AND  HIGH-TOWER  LADDER  DREDGES          93 

ing  the  lever,  controlling  the  main  engine  and  velocity  of  revolution 
of  buckets,  the  gypsy  engine  working  the  side  guys,  the  spuds  also 
being  raised  and  lowered  by  tackles  on  hoisting  drums.  The  digger 
may,  at  a  glance,  take  in  the  situation,  and  use  his  governing  wheels 
accordingly. 

The  cost  of  the  work  can  be  deduced  from  the  two  most  important 
items,  which  are  the  consumption  of  coal  and  the  wages  of  the  men 
handling  the  machine.  Mr.  Williams  gives  the  consumption  of 
coal  in  the  "  City  of  Paris  "  at  10  tons  per  day,  while  regarding  the 
men  he  says  that  at  the  Panama  Canal,  there  were  from  45  to  55 
men  on  these  machines,  distributed  as  follows: 

1  captain $300  per  month 

3  assistant  engineers 150 

3  firemen 70 

3  oilers 50 

3  diggers 65 

3  gypsymen 65 

1  steward  and  three  cooks 75 

6  waiter  boys 30 

22-32  seamen 50 

These  men  are  divided  into  three  watches  of  eight  hours  each, 
the  machines  working  night  and  day,  only  stopping  to  repair  machin- 
ery. Sunday  is  usually  occupied  in  replacing  any  worn-out  material, 
replacing  links,  and  anticipating  any  breakages  in  upper  tumbler 
bars,  boiler  tubes,  spud  gear,  etc. 

The  American  Contracting  &  Dredging  Co.  of  New  York  was 
paid  35  cents  per  cu.m.  and  notwithstanding  they  paid  such  high 
salaries  they  realized  over  50  per  cent  profit. 

More  recently  dredges  of  this  type  have  been  successfully  employed 
in  dredging  the  Siass  and  Swirs  Canals  in  Russia. 


CHAPTER  XIII 
HYDRAULIC  DREDGES— GENERAL  DISCUSSION 

IN  working  with  ladder  dredges  of  large  capacity  through 
different  materials,  European  engineers  discovered  that  it  was  more 
difficult  to  dredge  through  very  loose  material  than  in  soils  that 
were  hard  and  compact.  In  fine  sand  and  mud  the  impact  of  the 
buckets  scraping  the  bottom  caused  the  stirring  up  of  the  fine 
particles  of  the  soil,  to  such  an  extent  that  it  floated  away,  thus 
the  buckets  were  mostly  filled  with  water.  In  the  harbor  of  Cette, 
France,  a  ladder  dredge  that  used  to  excavate  180  cu.m.  per  hour 
of  coarse  sand  and  gravel  could  not  excavate  more  than  45  cu.m. 
of  fine  sand.  In  the  year  1867  M.  Basin,  a  French  engineer,  presented 
to  the  Paris  Exposition  a  model  of  a  new  type  of  dredge.  M.  Bazin 
proposed  to  raise  to  the  surface  the  loose  materials  by  means  of  a 
suction  pump.  The  same  method  was  suggested  again  in  1870  by 
Mr.  C.  Randolph,  and  in  the  following  year  it  was  used  by  Gen. 
Gillmore,  U.  S.  A.  in  dredging  the  channel  over  the  bar,  at  the 
mouth  of  the  St.  John's  River,  Florida. 

Hydraulic  dredges  are  of  very  simple  construction.  They  consist 
of  a  pipe  which  reaches  the  bottom  and  is  attached  to  a  powerful 
centrifugal  pump  discharging  the  materials  into  another  pipe, 
the  whole  being  mounted  on  a  float.  Owing  to  the  simplicity  of 
construction  hydraulic  dredges  can  be  built  at  a  smaller  cost  than 
ladder  dredges,  and  since  they  are  more  efficient  on  sandbars  or  at 
the  estuary  of  wide  rivers,  they  have  become  quite  common  and 
have  been  a  success  from  their  first  appearance. 

The  efficiency  of  the  hydraulic  dredge  has  been  continuously 
increased  and  to-day  we  have  machines  of  over  3000  cu.yds.  capacity 
per  hour.  The  cost  of  construction  of  these  machines  has  also 
increased  in  proportion.  To  give  continuous  employment  to  the 
hydraulic  dredges  they  are  now  built  to  work  through  hard  and 
compact  soils.  For  such  a  purpose  the  lower  end  of  the  suction 
pipe  is  provided  with  different  devices,  designed  to  dislodge  the 

94 


HYDRAULIC  DREDGES  95 

• 

materials  from  their  natural  beds,  and  break  the  soils  in  such  a 
manner  that  they  may  be  readily  taken  up  by  the  centrifugal 
pump. 

Suction  Pipe.  The  suction  pipe  is  usually  made  up  of  four  well- 
defined  parts,  which  are:  the  connection  to  the  pump, the  joint,  the 
tube  proper  and  the  agitator.  The  connection  to  the  pump  is  made 
by  an  iron  or  steel  pipe  running  on  deck  and  bent  in  such  a  manner 
as  to  connect  the  tube  proper  with  the  pump.  The  joint  as  a  rule 
is  made  of  rubber;  but  owing  to  the  wear  of  such  material,  it  requires 
continuous  repairing.  To  avoid  this  inconvenience,  connections 
are  now  being  made  on  some  dredges  by  means  of  a  ball-and-socket 
joint.  The  suction  tube  proper,  which  forms  the  real  communication 
between  deck  and  bottom,  is  composed  of  several  sections  of  wrought- 
iron  pipe  from  10  to  20  in.  in  diameter,  the  size  depending  upon  the 
efficiency  of  the  dredge.  These  pipes  are  made  up  of  sections  20 
ft.  in  length  each,  provided  with  flanges  and  riveted  together. 
They  can  be  also  made  of  steel  plates  welded  together.  Such  pipes 
are  stronger  and  lighter  than  those  made  of  wrought  iron.  It  can 
also  be  constructed  of  steel  angles  and  plates.  In  any  case  the 
suction  pipe  should  be  strong  in  order  to  support  either  the  agitator 
or  rotary  cutter  attached  at  its  lower  end  and  also  the  shafts  and 
gears  for  the  rotation  of  the  cutter.  The  length  of  this  portion 
of  the  suction  tube  varies  with  the  depth  and  nature  of  soil 
encountered. 

Its  length,  as  a  rule,  is  determined  in  such  a  way  as  to  have 
the  suction  pipe  working  at  an  angle  of  less  than  45°.  At  some 
convenient  point  the  suction  tube  is  provided  with  a  heavy  steel 
ring,  to  which  are  fastened  wire  ropes,  which  passing  over  sheaves 
suspended  from -a  gantry  at  the  end  of  the  boat,  are  wound  around 
the  drums  of  a  reversible  engine.  In  this  manner  it  is  possible  to 
raise  the  suction  tube  above  the  level  of  water  when  operations 
are  suspended,  and  lower  it  again  to  the  bottom  to  resume 
work. 

The  lower  end  of  the  suction  tube  is  usually  provided  with  some 
devices  to  feed  the  tube  in  the  most  convenient  way.  Of  the  various 
devices  the  most  commonly  used  ones  are:  the  scraper,  the  rotary 
cutter,  and  jets  of  water  or  compressed  air. 

Agitators.  The  scraperused  at  the  end  of  the  suction  tube  consists 
of  a  wide  broadened  extension  of  the  pipe  so  as  to  dig  a  furrow  as 
wide  as  possible.  It  is  covered  with  a  steel  apron  and  is  provided 


96 


A  TREATISE  ON  DREDGES  AND   DREDGING 


with  openings  on  the  lower  face  and  also  with  scrapers.  This  end 
attachment  of  the  pipe,  being  dragged  along  the  bottom,  scrapes 
the  soil,  which  enters  into  the  box  at  the  openings  and  is  drawn 
into  the  tube  by  the  force  of  the  pump.  Fig.  25  shows  the  Allen 
scraper  or  drag  as  designed  by  Mr.  J.  P.  Allen  and  used  in  the 
U.  S.  dredges  "Manhattan"  and  "Atlantic"  in  New  York 
Harbor. 

When  the  hydraulic  dredge  is  designed  to  work  through  hard 
soils  the  end  of  the  suction  tube  is  provided  with  a  cutter.  This 
consists  of  a  number  o£  knives  (10  to  15)  united  by  suitable  disks 
or  rings  at  one  or  both  ends.  The  knives  may  be  either  straight  or 
spiral,  mounted  around  and  concentric  with  the  end  of  the  suction 
pipe,  and  encased  in  a  cast-steel  hollow  shell  provided  with  open- 


FIG.  25.— Allen  Scraper  Used  on  the  U.  S.  Dredge  "Manhattan." 


ings.  The  blades  are  for  the  purpose  of  slicing  off  or  excavating  the 
material  and  feeding  it  into  the  interior  of  the  shell  through  the 
openings,  whence  it  is  drawn  into  the  pump.  The  efficiency  of 
a  cutter  depends  on  the  form  of  the  blades,  the  angles  at  which 
they  are  set  and  whether  they  are  straight  or  spiral,  and  on  the 
openings  between  them  and  at  the  bottom.  It  would  be  almost 
impossible  to  determine  absolutely  the  best  form  of  cutter  suitable 
for  any  material.  According  to  the  experience  of  Mr.  James  H. 
Apjohn,  M.  Inst.  C.E.,  a  cutter  with  its  straight  knives  set  at  an  angle 
of  26°  to  the  tangent  of  the  circle  round  which  they  were  placed 
and  overlapping  each  other  to  a  slight  extent,  worked  very  well 
in  loamy  soil,  but  when  the  clay  was  reached  the  openings  between 
the  blades  of  the  cutter  clogged  with  the  tenacious,  plastic  clay,  with 
the  result  that  the  proportion  of  clay  found  in  water  discharged 
through  the  pipe  line -was  extremely  small.  Another  cutter  with 


HYDRAULIC  DREDGES 


97 


narrow  spiral  knives  used  on  the  same  dredge  proved  to  be  more 
efficient  in  clay  than  the  first  one.  The  effect  of  the  cutters  of  work- 
ing in  sand  was  to  wear  the  blades  to  a  considerable  extent,  but  the 
bearings  kept  in  good  order,  the  sand  being  excluded  from  them  by 
an  arrangement  by  which  they  are  lubricated  by  water  under  pressure. 
From  Mr.  Apjohn's  experience  it  could  be  deduced  that  a  cutter 
with  spiral  knives  is  more  adaptable  for  soils  hard  and  compact; 
while  the  straight  blades  seem  very  efficient  in  loose  soils.  The 
rotary  motion  of  the  cutter  is  imparted  by  gears  and  shaftings 
placed  above  the  suction  pipe  and  operated  by  special  engines. 


FIG.  26.— Rotary  Cutter  at  the  End  of  Suction  Pipe. 

Fig.  26  shows  the  rotary  cutter  at  the  end  of  the  suction  pipe  of  a 
hydraulic  dredge. 

On  the  Chicago  Drainage  Canal  was  employed  a  hydraulic 
dredge  designed  by  Gen.  William  S.  Smith  of  Chicago.  This  dredge 
was  provided  with  a  new  device  for  loosening  and  mixing  the  material 
with  water.  Instead  of  a  rotating  cutter  at  the  end  of  the  suction 
pipe  a  series  of  hydraulic  jets  was  used.  A  pump  placed  near  the 
bow  of  the  boat  supplied  water  for  the  jets,  which  were  pont rolled 
by  -hand,  the  nozzles  being  fastened  to  long  poles.  The  jets 
loosened  the  muck  effectively  enough,  but  at  the  same  time 
they  forced  the  material  away  from  the  suction  pipe,  so  that  of  the 
total  volume  pumped  out  only  a  small  per  cent  was  solid  matter. 
Various  means  were  tried  in  an  effort  to  keep  the  muck  near  the 


98 


A  TREATISE  ON  DREDGES  AND   DREDGING 


suction  pipe,  after  being  loosened  by  the  jets,  but  without  suc- 
cess. 

For  working  in  sand,  water  jets  for  breaking  down  the  material 
to  be  dredged  are  preferred  to  rotary  cutters  by  engineers  on 
the  Mississippi  River.  At  first  water  jets  9  or  10  in  number  2^ 
to  3  in.  in  diameter  with  a  pressure  of  14  Ibs.  per  sq.in.  were 
used,  but  subsequently  much  better  results  were  obtained  by  jets 
1J  in.  in  diameter,  6  in  number,  with  a  pressure  of  65  Ibs.  per 
sq.in. 

Instead  of  jets  of  water  compressed  air  could  be  used  for  dislodging 


FIGS.  27  and  28. — Cross-section  and  Side  View  of  the  Centrifugal  Pump  of  a 

Hydraulic  Dredge. 

the  material  from  the  bottom,  but  the  same  objections  exist  against 
air  jets. 

Pump.  The  most  essential  part  of  the  hydraulic  dredge  is  the 
centrifugal  pump.  When  the  dredge  is  designed  to  work  only 
through  finely  divided  soils  any  pump  of  ordinary  construction 
will  be  found  satisfactory;  but  when  the  dredge  operates  through 
hard  and  compact  soils  special  attention  should  be  given  to  designing 
the  shell  of  the  pump,  which  should  be  strong  enough  to  resist  the 
violent  blows  caused  by  stones  thrown  against  the  inner  surface  of 
the  shell  by  the  impact  of  the  flowing  water  and  materials  carried  in 
suspension.  The  shell  is  usually  made  of  cast  steel  or  cast  iron. 


HYDRAULIC   DREDGES  99 

« 

cast  in  one  piece  of  round  cross  section,  the  dimensions  being  deter- 
mined by  the  required  capacity  of  the  dredge.  Owing  to  the  fact 
that  the  upper  part  of  the  shell  tends  to  break,  especially  when 
dredging  through  hardpan  and  gravel,  it  is  found  more  convenient 
to  have  the  shell  cast  in  two  separate  parts,  bolted  together  so  as  to 
renew  the  upper  part  when  damaged  without  being  compelled  to 
change  the  lower  one.  The  runner  or  impeller  consists  of  a  cast-steel 
disk  with  four  cast-steel  vanes  tapering  in  thickness  and  sharply 
curved  in  the  back  as  shown  in  Figs.  27  and  28,  which  is  an 
outline  of  one  of  the  pumps  used  for  sand  dredging  on  the  Missis- 
sippi River.  The  runners  can  also  be  made  with  5  blades,  as  in  the 
U.  S.  hydraulic  dredge  "  Delta,"  or  even  with  seven  blades,  as  in 
dredge  "  Epsilon,"  used  on  the  Mississippi  River. 

The  pumps  are  often  lined  with  steel  plates  for  the  purpose  of 
removing  the  lining  when  damaged  and  substituting  new  plates. 
Mr.  Robinson  states  that  the  delay  and  expense  of  renewing  the 
linings  amount  to  more  than  the  occasional  renewal  of  the  entire 
pump  shell,  as  the  latter  can  be  replaced  in  less  time  than  the  linings. 
Besides  the  bolts  or  fastenings  of  the  linings  tend  to  produce  abrasion 
and  wear  at  those  particular  points.  Wherever  there  is  a  crack 
or  joint  in  the  interior  of  the  pump  it  is  liable  to  produce  an  eddy 
or  change  of  direction  in  the  flow,  and  a  stream  of  gritty  material 
acting  in  this  way  will  soon  cut  out  the  fastenings  and  joints  of  the 
linings. 

Mr.  Robinson  says  that  the  interior  wear  of  the  pump  can  be 
greatly  reduced  by  careful  design.  It  is  better  to  allow  ample 
clearance  for  the  flow  at  all  points,  especially  the  periphery  of  the 
pump,  and  this  can  be  so  proportioned  that  the  abrasion  is  compar- 
atively slight  and  evenly  distributed.  If  experience  shows  that 
there  is  undue  wear  at  one  point,  it  means  that  there  is  a  stream 
of  gritty  material  flowing  or  impinging  against  the  surfaces  at 
that  point  and  at  a  high  velocity.  This  can  be  remedied  by  placing 
those  surfaces  further  away,  thus  giving  the  stream  more  room 
at  that  point.  Many  pump  designers  are  of  opinion  that  the  throat 
or  cut-off  of  the  interior  of  the  pump  should  be  as  close  as  possible  to 
the  periphery  of  the  pump  runner  in  order  to  prevent  any  flow 
past  this  point.  Careful  experiments  have  shown  that  this  makes 
very  little  difference,  and  for  dredging  pumps  especially  it  is  better 
to  allow  great  clearances  at  this  point,  otherwise  it  will  cause  great 
wear. 


100 


A  TREATISE  ON  DREDGES   AND   DREDGING 


The  following  table  shows  the  amount  of  solid  material  that 
can  be  raised  by  pumps  and  the  H.P.  required: 

TABLE  No.  1. 


No.  Pump 
(Diameter 
Discharge. 
Opening). 

Diameter 
Suction. 

Cubic  Yards  Material  per  Hour,  10  to  20  • 
Per  Cent  of  Solids. 

Horse-power 
Required 
for  Each 
10  Feet. 
Elevation. 

10  Per  Cent. 

15  Per  Cent. 

20  Per  Cent, 

4 

4 

14 

21 

28 

4 

6 

6 

30 

45 

60 

8 

8 

8 

60 

90 

120 

15 

10 

10 

90 

135 

180 

25 

12 

12 

125 

190 

250 

30 

15 

15 

210 

315 

420 

50 

18 

18 

300 

450 

600 

70 

20 

20 

360 

540 

720 

80 

24 

24 

480 

700 

960 

100 

32 

32 

900 

1350 

1800 

200 

36 

36 

1140 

1710 

2280 

250 

48 

48 

2040 

3220 

4080 

450 

Mr.  A.  W.  Robinson  states,  "  The  efficiency  of  a  good  centrifugal 
pump  for  water  is  from  55  to  65  per  cent  under  ordinary  conditions; 
that  of  a  dredging  pump  is  from  48  to  55  per  cent." 

Table  No.  2  gives  revolutions  of  various  kinds  of  centrifugal 
pumps,  while  Table  No.  3  gives  the  capacity  of  dredging  pumps. 
All  of  the  tables  in  this  chapter  are  taken  from  the  catalogue  of  the 
Morris  Machine  Works  of  Baldwinsville,  N.  Y.,  builders  of  centrifugal 
pumps. 

Discharge  Pipes.  Discharge  pipes  are  of  the  same  material  and 
dimensions  of  those  composing  the  suction  pipe.  The  discharge 
pipes  generally  rise  vertically  from  the  pump  and  then  bend  toward 
the  point  of  discharge.  When  the  suction  dredge  is  of  the  hopper 
type  the  discharge  pipes  run  into  the  sand  bins,  otherwise  they  are 
turning  toward  one  side  of  the  vessel  in  order  to  be  emptied  into 
scows  to  be  placed  alongside  of  the  vessel.  But  with  the  suction 
dredges  which  are  not  of  the  hopper  type,  trie  most  convenient 
way  of  disposing  of  the  debris  is  to  fill  up  lowlands  along  the  shores 
and  in  such  cases  the  discharge  pipe  is  connected  with  a  long  line  of 
pipe  placed  on  floats,  thus  conveying  the  dredged  materials  to  distant 
points. 

The  velocity  of  flow  in  the  discharge  pipe  varies  from  8  to  16  ft. 


HYDRAULIC  DREDGES 
TABLE  No.  2 


101 


REFERS  TO  SPEEDS  AT  WHICH  VERTICAL  PUMPS,  STANDARD 
PUMPS,  COMPOSITION  PUMPS,  AND  DOUBLE-SUCTION  PUMPS 
SHOULD  RUN  TO  RAISE  WATER  TO  DIFFERENT  HEIGHTS 


No. 

5  Feet. 

10  Feet. 

15  Feet, 

20  Feet. 

25  Feet. 

30  Feet. 

35  Feet. 

1J 

428 

604 

739 

854 

955 

1045 

1131 

If 

348 

491 

601 

695 

777 

850 

920 

2 

272 

384 

472 

545 

607 

665 

720 

2i 

272 

384 

472 

545 

607 

665 

720 

3" 

272 

384 

472 

545 

607 

665 

720 

4 

230 

364 

447 

515 

574 

630 

680 

5 

206 

289 

354 

410 

457 

500 

541 

6 

172 

242 

295 

341 

381 

418 

452 

8 

148 

207 

250 

293 

327 

359 

387 

10 

135 

190 

233 

270 

300 

329 

355 

12 

107 

151 

185 

213 

238 

261 

282 

12* 

206 

289 

354 

410 

457 

500 

541 

15 

83 

116 

142 

164 

183 

201 

217 

15* 

121 

171 

209 

241 

270 

295 

319 

18 

83 

116 

142 

164 

183 

201 

217 

18* 

121 

171 

209 

241 

270 

295 

319 

20 

115 

162 

197 

228 

255 

280 

302 

24* 

104 

146 

178 

.  206 

230 

253 

272 

24 

77 

108 

132 

152 

170 

187 

201 

No. 

40  Feet. 

50  Feet. 

60  Feet. 

70  Feet. 

80  Feet, 

90  Feet. 

100  Feet. 

1* 

1208 

1351 

1481 

1599 

1714 

1813 

1911 

If 

982 

1099 

1205 

1301 

1394 

1475 

1554 

2 

773 

858 

940 

1030 

1085 

1150 

1215 

2* 

773 

858 

940 

1030 

1085 

1150 

1215 

3 

773 

858 

940 

1030 

1085 

1150 

1215 

4 

727 

812 

890 

960 

1025 

1085 

1145 

5 

579 

647 

712 

765 

817 

867 

914 

6 

483 

540 

591 

638 

683 

722 

763 

8 

415 

464 

510 

548 

586 

620 

655 

10 

380 

425 

647 

502 

538 

568 

600 

12 

302 

337 

371 

400 

436 

452 

476 

12* 

579 

647 

712 

765 

817 

867 

914 

15 

232 

259 

286 

307 

328 

348 

368 

15* 

342 

382 

420 

451 

483 

511 

539 

18 

232 

259 

286 

307 

328 

348 

368 

18* 

342 

382 

420 

451 

483 

511 

539 

20 

323 

361 

395 

426 

456 

483 

510 

24* 

291 

326 

358 

384 

412 

436 

459 

24 

215 

241 

263 

284 

304 

322 

340 

*  Refers  to  low-lift  pumps. 

If  pumps  are  run  at  above  speeds  they  will  deliver  quantities  of  water  stated 
in  Table  No.  3.  If  water  is  to  be  forced  through  long  pipes  or  through  many 
elbows,  speed  must  be  increased  to  correspond.  The  above  pumps  can  all  raise 
water  100  ft.,  but  should  be  made  extra  heavy  for  elevations  above  60  ft.,  and 
for  best  results  high-pressure  type  of  pumps  should  be  used. 


102 


A  TREATISE  ON   DREDGES   AND   DREDGING 


TABLE  No.  3 

CAPACITY  IN  GALLONS  PER  MINUTE  DISCHARGED  AT  VELOCITIES 
IN  FEET  PER  SECOND,  FROM  3  TO  15.  ALSO  FRICTION 
HEAD  IN  FEET  PER  100  FEET  LENGTH  OF  PIPE. 


Diam. 

Pipe. 

1-inch. 

2-inch. 

3-inch. 

4-inch. 

Diam. 
Pipe. 

Veloc- 
ity. 

Capac- 
ity. 

Friction. 

Capac- 
ity. 

Friction. 

Capac- 
ity. 

Friction. 

Capac- 
ity. 

Friction. 

Veloc- 
ity. 

3 

7.34 

4.08 

29.37 

2.04 

66.09 

1.36 

117.50 

1.02 

3 

4 

9.79 

6.83 

39.16 

3.41 

88.12 

2.27 

156.67 

1.71 

4 

5 

12.24 

10.2 

48.95 

5.12 

110.15 

3.41 

195.70 

2.56 

5 

6 

14.68 

14.3 

58.74 

7.16 

132.18 

4.78 

235.84 

3.58 

6 

7 

17.13 

19.0 

68.53 

9.54 

154.21 

6.36 

274  .  98 

4.77 

8 

19.58 

24.5 

78.32 

12.2 

176.24 

8.16 

314.12 

6.12 

8 

8* 

20  .80 

27.4 

83  .  23 

13.7 

187  .  25 

9.15 

333  .  75 

6.86 

8* 

9 

22.03 

30.5 

88.11 

15.2 

198.27 

10.1 

352.26 

7.64 

9 

9* 

23.25 

33.8 

93.00 

16.9 

209.24 

11.2 

371.90 

8.46 

9* 

10 

24.48 

37.3 

97.90 

18.6 

220.30  i      12.4 

391.40 

9.33 

10" 

10* 

25.70 

40.9 

102.80 

20.4 

231.31   !      13.6 

411.05 

10.2 

11 

26.92 

44.7 

107.69 

22.3 

242.33  i      14.9 

430.54 

11.1 

11" 

11* 

28.15 

48.7 

112.58 

24.3 

253.34  i      16.2 

450  .  20 

12.1 

11* 

12 

29.37 

52.8 

117.48 

26.4 

264.36 

17.6 

470.68 

13.2 

12 

13 

31.82 

61.5 

127.27 

30.7 

286.39 

20.5 

509.82 

15.3 

13 

14 

34.27 

71.0 

137.06 

35.5 

308  .  42 

23.7 

548.96 

17.7 

14 

15 

36.72 

81.0 

146.85 

40.5 

330.45 

27.0 

587.10 

20.3 

15 

Pipe.' 

5-inch. 

6-inch. 

7-inch. 

8-inch. 

Diam. 

Pipe. 

Veloc- 
ity. 

Capac- 
ity. 

Friction. 

Capac- 
ity. 

Friction. 

Capac- 
ity. 

Friction. 

Capac- 
ity. 

Friction. 

Veloc- 
ity. 

3 

183.63 

.816 

264.24 

.68 

359.79 

.583 

470.04 

.510 

3 

4 

244.84 

1.36 

352  .  32 

1.13 

479.72 

.976 

626.72 

.854 

4 

5 

306.05 

2.05 

440.40 

1.70 

599.65 

1.46 

783.40 

1.28 

5 

6 

367  .  26 

2.86 

528.48 

2.38 

719.58 

2.05 

940.08 

1.79 

6 

7 

428.47 

3.81 

616.56 

3.18 

839.51 

2.72 

1096.7 

2.38 

7 

8 

489.68 

4.90 

705.64 

4.08 

959.44 

3.49 

1253.4 

3.06 

8 

8* 

520.61 

5.49 

749.01 

4.57 

1019.4 

3.92 

1331.5 

3.43 

8* 

9 

550.89 

6.11 

793  .  72 

5.09 

1079.4 

4.36 

1410.1 

3.82 

9 

9* 

581  .  25 

6.77 

837.08 

5.61 

1139.4 

4.83 

1488.0 

4.23 

9* 

10 

612.10 

7.46 

831.83 

6.21 

1199.3 

5.33 

1566.8 

4.b6 

10 

10* 

642.43 

8.19 

925.23 

6.82 

1259.3 

5.84 

1645.8 

5.22 

10* 

11 

673.31 

8.95 

969  .  88 

7.45 

1319.2 

6.39 

1723.5 

5.59 

11 

11* 

703.62 

9.74 

1013.3 

8.11 

1379.2 

6.95 

1801.5 

6.08 

11* 

12 

734  .  52 

10.5 

1057.9 

8.83 

1439.2 

7.54 

1880.2 

6.60 

12 

13 

795.73 

12.3 

1145.0 

10.2 

1559.1 

8.79 

2036.8 

7.00 

13 

14 

856.94 

14.2 

1233.1 

11.8 

1679.0 

10.1 

2193.5 

8.87 

14 

15 

918.15 

16.2 

1321.2 

13.5 

1799.0 

11.6 

2350  2 

10.1 

15 

Diam. 
Pipe. 

9-inch. 

10-inch. 

12-inch. 

14-inch. 

Diam. 
Pipe. 

Veloc- 
ity. 

Capac- 
ity. 

Friction. 

C?tpyac-     Friction. 

Capac- 
ity. 

Friction. 

Capac- 
ity. 

Friction. 

Veloc- 
ity. 

3 

594.  78!        .453 

734.40         .408 

1057.5 

.347 

1439.0 

.291 

3 

4 

793.04         .759 

979.20         .683 

1410.0 

.581 

1919.7 

.488 

4 

5 

991.30      1.13 

1224.0         1.02 

1762.6 

.871 

2399.4 

.731 

5 

6 

1189.5 

1.59 

1488.8  :      1.43 

2115.1 

1.21 

2878.0 

1.02 

6 

7 

1388.8 

2.12 

1713.6 

1.90 

2467.6 

1.62 

3358  .  7 

1.36 

7 

8 

1586.0 

2.72 

1958.4 

2.45 

2320.1 

2.08 

3838.4 

1.75 

8 

1685.0 

3.05 

2380.8 

2.74 

2396.3 

2.33 

4078  .  3 

1.96 

8* 

9 

1784.3 

3.40        2203.2 

3.05 

3172.7 

2.60 

4318.  1 

2.18 

9 

9* 

1883.5 

3.76     i   2325.6 

3.38 

3348.9 

2.88 

4558.0 

2.42 

9* 

10 

1982.6 

4.14 

2448.0 

3.73 

3525.2 

3.17 

4798  .  0 

2.66 

10 

10* 

2082.7 

4.55 

2570.8 

4.09 

3701.4 

3.48 

5037.7 

2.92 

10* 

11 

2181.9 

4.97 

2692.8 

4.47 

3877  .  7 

3.80 

5277  .  5 

3.19 

11 

2280.  (> 

5.41 

2815.2 

4.87 

4053.8 

4.14 

5517.4 

3.48 

11* 

12 

2279.1 

5.87 

2937.6 

5.28 

4230  .  2 

4.49 

5757  .  2 

3.77 

12 

13 

2577.4 

6.84 

3182.4 

6.15 

4582  .  8 

5.23 

6237  .  8 

4.40 

13 

14 

2776.6 

7.88 

3427  .  2 

7.10 

4935  .  4 

6.03 

6717.5 

5.06 

14 

15 

2974.9 

9.00 

3672.0 

8.10 

5287  .  8 

6.89 

7107.2 

5.79 

15 

HYDRAULIC  DREDGES 


103 


TABLE  No.  3 
CAPACITY  IN  GALLONS  PER  MINUTE  DISCHARGED— Confirmed 


Diam. 
Pipe. 

15-inch. 

18-inch. 

20-inch. 

22-inch. 

Diam. 
Pipe. 

Veloc- 
ity. 

Capac- 
ity. 

Friction. 

Capac- 
ity. 

Friction. 

Capac- 
ity. 

Friction. 

Capac- 
ity. 

Friction 

Veloc- 
ity. 

3 

1652.2 

.272 

2379  .  7 

.227 

2937 

.204 

3554  .  1 

.185 

3 

4 

2203  .  0 

.455 

3172.6 

.379 

3916 

.342 

4739.8 

.310 

4 

5 

2754  .  7 

.682 

3965  .  5 

.569 

4896 

.512 

5924  .  5 

.465 

5 

6 

3304:4 

.955 

4758  .  4 

.795 

5875 

.717 

7108.2 

.651 

6 

3855  .  2 

1.27 

5552  .  3 

1.06 

6854 

.954 

8293.9 

.866 

7 

8 

4406.9 

1.63 

6345.2 

1.36 

7833 

1.22 

9478  .  6 

1.11 

8 

8* 

4688  .  1 

1.82 

6741.9 

1.52 

8323.6 

1.37 

10071 

1.25 

81 

9" 

4957  .  7 

2.04 

7138.1 

1.70 

8812 

1.53 

10663 

1.39 

9 

9* 

5232.1 

2.25 

7534.8 

1.88 

9302.6 

1.69 

11255 

1.54 

91 

10" 

5508.4 

2.50 

7931.0 

2.07 

9792 

1.87 

11848 

1.69 

10 

101 

5783.4 

2.73 

8328.8 

2.27 

10281 

2.05 

12440 

1.86 

101 

11 

6058.2 

2.98 

8724.9 

2.48 

10771 

2.24 

13033 

2.03 

11 

iH 

6334.6 

3.25 

9121.7 

2.70 

11258 

2.43 

13625 

2.21 

111 

12 

6609.9 

3.52 

9517.8 

2.93 

11750 

2.64 

14217 

2.40 

12 

13 

7160.6 

4.10 

10310 

3.42 

12729 

3.08 

15402 

2.79 

13 

14 

7711.4 

4.73 

11104 

3.93 

13708 

3.55 

16587 

3.22 

14 

15 

8262 

5.40 

11897 

4.50 

14688 

4.05 

17772 

3.68 

15 

Diam. 
Pipe. 

24-inch. 

26-inch. 

28-inch. 

30-inch. 

Diam. 
Pipe. 

Veloc- 
ity. 

Capac- 
ity. 

Friction. 

Capac- 
ity. 

Friction. 

Capac- 
ity. 

Friction. 

Capac- 
ity. 

Friction 

Veloc- 
ity. 

3 

4230.3 

.170 

4964  .  2 

.157 

5757  .  2 

.146 

6609 

.136 

3 

4 

5640.0 

.284 

6619.0 

.262 

7676  .  2 

.244 

8812 

.227 

4 

5 

7050  .  8 

.426 

8274  .  7 

.394 

9596  .  3 

.366 

11015 

.341 

5 

6 

8460.6 

.597 

9929.5 

.550 

11514 

.512 

13218 

.478 

6 

7 

9870  .  3 

.794 

11583 

.753 

13434 

.681 

15421 

.636 

7 

8 

11280 

1.01 

13238 

.940 

15353 

.875 

17624 

.816 

8 

81 

11985 

1.14 

14066 

1.05 

16316 

.980 

18725 

.915 

81 

9 

12690 

1.27 

14893 

1.17 

17273 

.09 

19827 

1.01 

9 

91 

13395 

1.40 

15721 

1.30 

18231 

.21 

20928 

1.12 

91 

10 

14100 

1.55 

16548 

1.43 

19192 

.33 

22030 

1.24 

10 

101 

14805 

1.70 

17375 

1.57 

20150 

.46 

23131 

1.36 

101 

11 

15510 

1.86 

18202 

1.72 

21111 

.60 

24233 

1.49 

11 

111 

16215 

2.03 

19029 

1.87 

22069 

.74 

25338 

1.62 

111 

12 

16920 

2.20 

19857 

2.03 

23030 

.89 

26436 

1.76 

12 

13 

18330 

2.56 

21511 

2.36 

24950 

2.20 

28639 

2.05 

13 

14 

19740 

2.95 

23166 

2.73 

26869 

2.53 

30842 

2.37 

14 

15 

21150 

3.37 

24824 

3.11 

28788 

2.89 

33045 

2.70 

15 

Diam. 
Pipe. 

32-inch. 

36-inch. 

,  1- 

42-inch. 

48-inch. 

Diam'. 
Pipe. 

Veloc- 
ity. 

Capac- 
ity. 

Friction. 

Capac- 
ity. 

Friction. 

Capac- 
ity. 

Friction. 

Capac- 
ity. 

Friction. 

Veloc- 
ity. 

3 

7519.7 

.127 

9518 

.113 

12954 

.097 

16921 

.085 

3 

4 

10026 

.213 

12690 

.189 

17272 

.163 

22561 

.143 

4 

5 

12532 

.320 

15863 

.284 

21590 

.244 

28201 

.213 

5 

6 

15039 

.447 

19036 

.397 

25908 

.341 

33841 

.298 

6 

7 

17546 

.591 

22208 

.528 

30226 

.454 

39482 

.397 

7 

8 

20052 

.764 

25381 

.679 

34544 

.583 

45122 

.510 

8 

8i 

21306 

.857 

26967 

.760 

36704 

.653 

47942 

.571 

81 

9 

22559 

.954 

28554 

.847 

38863 

.728 

50762 

.636 

9 

91 

23812 

1.06 

30140 

.938 

41022 

.806 

53582 

.694 

91 

10 

25065 

1.16 

31726 

1.03 

43181 

.888 

56403 

.778 

10 

104 

26319  , 

1.28 

33313 

1.13 

45340 

.975 

59223 

.851 

101 

11 

27572 

1.40 

34899 

1.16 

47499 

1.06 

62043 

.930 

11 

111 

28825 

1.52 

36485 

1.35 

49658 

1.16 

64863 

.00 

HI 

12 

30379 

1.65 

38072 

1.46 

51817 

1.26 

67683 

.10 

12 

13 

32585 

1.92 

41244 

1.70 

56135 

1.46 

73324 

.28 

13 

14 

35092 

2.21 

44417 

1.97 

60453 

1.69 

78964 

.48 

14 

15 

37598 

2.53 

47590 

2.24 

64771 

1.93 

84604 

.69 

15 

104  A  TREATISE  ON  DREDGES  AND   DREDGING 

per  second,  and  different  kinds  of  material  require  different  veloci- 
ties of  flow  for  the  most  efficient  work.  Material  like  clay  or  soft 
mud  can  be  transported  at  a  slower  velocity  than  sand  or  gravel 
materials,  which  tend  to  precipitate  quickly.  A  high  velocity  of  flow 
means  a  greater  friction  in  the  pipe  and  pump  and  consequently 
greater  expenditure  of  power.  A  fluid  mixture  of  sand  or  mud  and 
water  is  heavier  than  water  alone,  and  therefore  takes  more  power 
to  pump  it  against  a  given  head,  and  also  the  friction  in  the  pipe 
is  greater. 

European  engineers  call  the  hydraulic  dredges,  suction  dredges; 
but  Mr.  Robinson  advocates  calling  them  hydraulic,  from  the  fact 
that  the  suction  principle  is  not  employed  at  all  in  dredging,  but 
simply  in  conveying  the  debris  from  the  bottom  to  the  discharge. 
Such  an  explanation  is  necessary  in  order  to  prevent  confusion  in 
quoting  from  Engineering  and  other  European  papers,  in  which 
these  machines  are  described  under  the  head  of  suction  dredges. 

In  hydraulic  dredges  a  very  large  volume  of  water  is  pumped 
in  connection  with  the  material,  consequently  a  large  percentage  of 
the  power  is  wasted  in  useless  work.  They  are  therefore  subjected 
to  the  same  criticism  as  the  high-tower  ladder  dredges.  But  also 
there  the  consideration  of  the  economical  disposal  of  the  dredged 
materials  will  show  in  the  end  that  they  are  not  as  wasteful  as  they 
appear  at  first.  In  fact  the  debris  can  be  conveyed  to  a  great 
distance  by  the  simple  action  of  the  pump,  and  the  large  quantity 
of  water  carrying  in  suspension  the  debris  allows  the  even  deposit 
of  the  materials  over  a  large  surface.  Besides,  the  suction  dredge 
working  continuously  day  and  night  is  found  to  be  both  efficient 
and  economical,  more  so  than  other  types  of  dredges. 

Hydraulic  dredges  can  be  grouped  into  sea-going  and  those  used 
for  channel  or  river  improvements;  the  latter  group  can  be  divided 
according  to  Mr.  Robinson  in  regard  to  their  feedings  as  follows: 

(a)  Lateral  feeding  or  ship-channel  type  with  floating  discharging 
pipe. 

(6)  Forward  feeding  or  Mississippi  type  with  floating  discharging 
pipe. 

(c)  Radial  feeding  with  spud  anchorage  and  floating  discharging 
pipe. 

These  different  types  of  hydraulic  dredges  will  be  described 
in  the  following  chapters. 


CHAPTER  XIV 
SEA-GOING   HYDRAULIC  DREDGES 

SEA-GOING  hydraulic  dredge 3  are  of  two  types,  those  in  which 
the  hull  is  built  like  that  of  any  ordinary  steamer,  having  on  board 
all  the  required  machinery  and  accommodation  for  the  crew,  and 
those  in  which  the  hull  is  of  larger  dimensions  to  provide  room  for 
the  hopper  to  store  the  excavated  material.  The  former  type  of 
dredge  is  simply  an  excavating  machine,  while  the  latter  type  can 
be  considered  as  an  excavating  and  transporting  machine.  Consid- 
ering these  two  types  of  dredges  from  the  point  of  view  of  excava- 
tion, they  are  identical,  the  only  difference  being  that  in  one 
case  the  debris  is  conveyed  into  the  hoppers  by  means  of  a  chute, 
while  in  the  other  case  the  chute  conveys  the  materials  to  the  sides 
so  as  to  be  loaded  into  scows.  To  avoid  a  useless  repetition  only 
the  hydraulic  dredges  of  the  hopper  type  will  be  discussed. 

The  sea-going  hydraulic  hopper  dredges  perform  the  double 
function  of  dredging  and  transporting  the  debris  so  as  to  be  dumped 
in  convenient  places,  into  deep  waters.  In  order  to  unload  the  de*bris 
away  from  the  shore  so  that  the  tides  will  not  bring  back  any 
part  of  it,  the  steamers  generally  go  not  less  than  8  or  10  miles 
from  shore.  For  this  reason  their  hulls  must  be  strongly  built  to 
stand  well  in  any  kind  of  rough  weather.  The  hull  is  usually  built 
of  steel,  but  there  are  several  suction  dredges  used  by  the  U.  S. 
Government  for  harbor  and  river  improvements  along  the  Atlantic 
and  Gulf  coasts  that  have  wooden  hulls  covered  with  copper  plates. 
Wooden  hulls  are  preferred  on  work  at  shallow  depths  on  account 
of  wood  being  more  elastic  than  steel,  the  wooden  dredge  being 
better  able  to  resist  the  inevitable  pounding  on  shallow  bars.  Hulls 
are  built  of  large  dimensions  in  order  to  have  large  space  for  the 
hoppers,  thus  carrying  on  each  trip  as  much  as  possible  of  the  dredged 
materials.  Yet  these  dimensions  should  be  kept  within  certain 
limits  so  as  not  to  require  extra  heavy  and  expensive  engines,  which 
tend  to  greatly  increase  both  the  original  cost  of  the  dredge  and 

105 


106  A  TREATISE   ON   DREDGES   AND   DREDGING 

its  running  expenses.  Thus  the  capacity  of  the  hoppers  is  kept 
between  2000  and  3000  cu.yds.  The  hull  is  divided  in  different 
compartments  separated  by  watertight  bulkheads. 

The  hopper  for  the  reception  of  the  dredged  materials  is  con- 
structed in  different  manner.  It  generally  consists  of  two  rows  of 
bins  located  amidship  on  each  side  of  the  vessel  in  order  to  leave  the 
pit  in  their  middle  for  the  suction  pipe  as  in  the  dredge  "  Thomas ," 
or  they  are  simply  located  side  by  side  divided  longitudinally  as  in 
the  dredge  for  the  Seine  River  hereafter  illustrated.  The  hoppers  can 
also  be  located  one  forward  and  the  other  aft  of  the  vessel,  separated 
amidship  by  the  space  for  the  boilers  and  engines,  as  in  the  dredges 
"  Manhattan  "  and  "Atlantic."  In  such  cases  the  hopper,  being  as 
wide  as  the  vessel,  must  be  well  braced  and  strongly  built  to  resist 
the  pressure  of  the  wet  materials  upon  the  walls  of  the  wide  hopper. 
The  bottom  of  the  hopper  is  generally  made  in  the  shape  of  several 
inverted  frustra  of  pyramids  for  the  purpose  of  facilitating  the 
descent  of  the  materials  by  sliding  along  the  walls  of  these  pyramids. 
The  floor  of  each  frustrum  is  formed  by  a  gate  or  valve  which  can 
be  opened  at  will.  These  gates  or  valves  are  built  of  various  designs, 
the  one  most  commonly  used  being  in  the  shape  of  a  flap  hinged  at  one 
side  to  the  hull  and  operated  by  a  chain  at  the  free  end.  The  chains 
are  attached  to  a  horizontal  shaft  placed  on  deck  and  revolved  by 
a  system  of  cog-wheels  moved  by  an  engine.  By  revolving  this 
shaft  all  the  chains  are  drawn  in  or  payed  out,  thus  opening  and 
closing  simultaneously  all  the  various  compartments  of  the  hopper. 
Conical  valves  are  also  used  to  close  up  the  bottom  of  the  various 
compartments  of  the  hopper.  In  such  a  case  the  four  walls  of  the 
inverted  frustrum  of  the  pyramid  converges  toward  the  bottom 
and  end  in  a  circle  strongly  reinforced  with  iron  rings.  Into  these 
rings  fit  heavy  conical  shaped  valves,  and  the  various  compartments 
of  the  hopper  are  opened  or  closed  by  simply  raising  or  lowering 
these  valves.  The  operation  of  dumping  can  be  done  while  the  vessel 
is  in  motion. 

The  materials  removed  from  the  bottom  by  hydraulic  dredges 
are  always  mixed  with  a  large  quantity  of  water  in  such  a  way  that 
the  hopper  will  be  found  filled  up  with  more  water  than  solid  mater- 
ials. To  avoid  this  the  hoppers  are  always  provided  with  several 
overflows,  to  carry  off  the  water. 

Besides  hydraulic  dredges  with  hoppers  able  to  unload  their 
contents  by  gravity  in  the  manner  just  described,  there  have  also 


SEA-GOING   HYDRAULIC  DREDGES 


107 


been  constructed  hydraulic  dredges  in  which  the*  materials  stored 
in  the  hoppers  can  be  transported  to  some  point  distant  from  the 
vessel  by  means  of  pumping  through  a  pipe  line.  In  such  a  case 
the  bottom  of  the  hopper  is  constructed  in  a  different  manner. 
This  new  method  was  introduced  in  the  dredge  "  Nereus,"  built  by 
Messrs.  Smit  &  Sons  for  the  removal  of  the  bar  of  the  Liffey  in 
connection  with  the  improvements  of  Dublin  Harbor. 

In  the  hydraulic  hopper  dredge  "  Nereus  "  the  bottom  of  the 
hopper  is  formed  by  two  sets  of  flaps,  Fig.  29;  one  of  these  open 
in  the  usual  way,  being  hinged  to  one  side  and  controlled  by 
chains  on  the  opposite  end.  At  some  distance  above  these  flaps 


FIG.  29. — Hoppers  in  the  Hydraulic  Dredge  "Nereus." 

there  are  others  which  form  the  real  bottom  of  the  hopper.  The 
space  between  these  two  sets  of  flaps  forms  a  chamber  which  can  be 
filled  with  water  and  for  this  purpose  holes  are  left  at  the  bottom 
of  the  chamber.  Water  can  be  also  supplied  to  the  chamber  by 
means  of  a  special  tank  located  011  deck.  When  the  dredge  is 
operated  as  any  ordinary  hopper  dredge  the  upper  set  of  flaps 
are  left  open  and  the  debris  will  fill  the  chamber  abutting  directly 
against  the  large  flaps,  and  are  dumped  in  the  usual  way  by 
simply  opening  these  flaps.  But  when  the  dredge  must  trans- 
port the  debris  to  distant  points  and  then  pump  it  to  land  by 
means  of  a  discharge  pipe  the  operation  is  made  in  a  different  way. 
The  small  flaps  are  closed  and  form  the  floor  of  the  hopper.  The 
large  flaps  are  closed  also  and  the  chamber  is  filled  with  water 


108  A  TREATISE   ON  DREDGES  AND   DREDGING 

entering  from  the  holes.  In  this  manner  the  materials  stored 
in  the  hoppers  can  be  transported  to  any  place.  To  dump  the 
debris  one  set  of  small  flaps  is  open  at  a  time ;  the  contents  of  the 
compartment  of  the  hopper  will  fall  into  the  chamber  and  the  material 
mixed  with  water  will  be  in  condition  to  be  raised  by  a  sand  pump. 
This  pump  will  also  force  the  material  through  a  discharge  pipe, 
thus  conveying  the  debris  to  land.  In  case  the  quantity  of  water 
entering  from  the  holes  is  not  sufficient  to  dilute  the  material,  water 
is  taken  from  the  tank  on  deck. 

In  regard  to  the  dredging  apparatus  the  hydraulic  hopper  dredges 
can  be  built  either  with  a  single  suction  pipe  and  a  centrifugal 
pump  located  amidship,  when  the  hull  is  provided  with  a  well  for 
the  suction  pipe  like  in  the  dredge  "Thomas";  or  the  dredge  is 
constructed  with  two  centrifugal  pumps,  one  located  on  each  side 


FIG.  30. — Sand  Pump  on  Dredge  "Nereus." 

of  the  vessel  and  alimented  by  a  suction  pipe,  each  pump  discharging 
into  a  separate  hopper.  In  this  manner  are  built  the  dredges  for 
the  Seine  River  and  those  of  the  U.  S.  Government  employed 
in  the  Ambrose  Channel  in  New  York  Harbor.  The  ends  of  the 
suction  pipes  may  be  furnished  with  either  a  simple  grating  or  an 
excavator  of  the  drag  or  cutter  type.  When  there  is  only  a  grating 
or  a  drag  the  suction  pipe  is  inclined  toward  the  stern,  while  when 
there  is  an  excavator  the  suction  pipe  is  feeding  forward  and  is 
inclined  toward  the  bow.  Since  the  hydraulic  hopper  dredge  is 
usually  designed  to  work  in  places  exposed  to  stormy  weather  and  on 
account  of  its  great  running  expenses  it  must  work  even  in  heavy 
seas,  special  attention  should  be  given  to  the  joint  of  the  suction 
pipe  of  the  pump  in  order  that  the  dredging  be  not  affected  by  the 
rolling  of  the  vessel  and  without  straining  the  joint  to  such  an 
extent  as  to  impair  its  safety. 

From  the  reason  that  the  dredging  operations  should  be  con- 


SEA-GOING  HYDRAULIC  DREDGES  109 

0 

tinued  during  heavy  seas  the  pump  should  be  so  designed  as  to  be 
able  to  fill  the  hopper  in  the  shortest  time  possible.  As  a  rule  it 
takes  from  40  to  50  minutes  to  fill  the  hoppers  of  the  capacity  indi- 
cated above. 

Several  engines  are  required  for  the  service  of  the  sea-going 
suction  hopper  dredges,  the  most  important  being  those  for  the 
purpose  of  propelling,  pumping,  lighting,  steering,  hoisting  both 
the  suction  pipes  and  the  anchors,  opening  the  gates  of  the  hoppers, 
etc.  This  kind  of  dredge  being  always  in  motion,  should  be 
provided  with  powerful  propelling  engines  which  will  insure  to 
the  vessel  a  speed  of  at  least  7  knots  per  hour  when  loaded  and  not 
less  than  10  knots  when  light.  Each  pump  is  furnished  power  by 
an  engine  of  the  marine  type  with  vertical  cylinders  and  so  designed 
as  to  overcome  100  ft.  of  head  of  water  and  causing  the  runners 
to  make  from  200  to  300  revolutions  per  minute.  Electricity  for 
the  ordinary  illumination  of  the  vessel  as  well  as  for  the  arc  lamps 
used  on  deck  during  the  night  work  and  for  the  searchlights  is 
provided  by  a  high-speed  engine  belted  to  a  dynamo.  The  hoisting 
engines  for  lifting  the  suction  pipes  and  the  anchors  are  of  the  usual 
duplex  type  with  two  horizontal  cylinders.  Similar  engines  are 
used  for  the  opening  and  closing  of  the  gates  of  the  hoppers 
when  no  other  methods  are  used,  and  the  steering  is  also  done  by 
a  small  steam  engine.  Steam  is  provided  by  marine  boilers  of 
sufficient  capacity  for  the  working  of  all  the  various  engines  simul- 
taneously. 

The  manner  of  working  with  the  sea-going  hydraulic  hopper 
dredges  is  as  follows:  When  the  dredge  has  reached  the  site  of 
excavation  the  suction  pipes  are  lowered  until  the  drags  or  cutters 
reach  the  bottom  and  then  the  steamer  moves  ahead  at  a  slow 
speed  while  the  pumps  are  put  in  action.  In  this  manner  one  or 
two  furrows  are  dug  on  the  bottom  according  to  the  number  of 
suction  pipes,  along  the  course  of  the  steamer,  the  width  and  depth 
of  these  furrows  depending  upon  the  device  used  at  the  end  of  the 
suction  pipe.  Mr.  Babcock  states  that  the  U.  S.  dredges  in  New 
York  Harbor  are  each  provided  with  two  drags  5  ft.  wide  and 
located  52  ft.  apart.  Two  furrows  are  thus  excavated,  taking  in 
a  load  of  2500  cu.yds.,  approximately  1800  cu.yds.  in  place,  in  a 
course  15,000  to  20,000  ft.  long.  The  courses  were  laid  out  of  such 
a  length  that  the  dredge  could  get  a  full  load  in  going  up  and  back 
once.  This  made  a  shorter  trip  to  the  dump  and  saved  time  by 


110  A  TREATISE  ON    DREDGES   AND   DREDGING 

avoiding  unnecessary  turns.  The  dredges  began  to  work  at  5  A.M.  on 
Monday  and  did  not  return  to  the  docks  until  Saturday  at  noon, 
working  continuously  day  and  night,  stopping  only  for  holidays  or 
repairs.  The  efficiency  of  the  work  at  night  was  estimated  at  90 
per  cent  of  that  done  in  daytime. 

As  previously  stated,  Gen.  Gillmore  used  the  hydraulic  dredge 
of  the  hopper  type  in  1871,  thus  the  honor  of  first  using  this  type 
belongs  to  the  United  States.  The  following  description  is  slightly 
condensed  from  a  paper  by  Gen.  Gillmore  and  published  in  Van 
Nost rand's  Magazine,  September,  1872: 

A  novel  device,  he  says,  for  utilizing  the  powers  of  the  centrifugal 
pump,  has  recently  been  put  in  successful  operation  by  the  writer, 
in  deepening  the  channel  over  the  bar  at  the  mouth  of  the  St.  John's 
River,  Florida.  Upon  this  bar  the  ocean  swell,  which  constantly 
prevails,  is  of  such  exceptional  magnitude  and  violence  that  the 
usual  method  of  dredging  into  lighters  or  scows,  ordinarily  pursued 
in  still  water,  is  entirely  impracticable. 

After  futile  attempts  to  get  the  bar  channel  deepened  by  contract, 
the  following  plan  was  adopted,  viz. :  To  provide  a  suitable  steamer 
and  fit  her  out  with  a  9-in.  centrifugal  pump,  two  branches  of  6-in. 
suction  pipe,  and  timber  bins  on  deck  for  holding  the  sand  pumped 
up  from  the  bottom. 

The  steamer  used,  the  "  Henry  Burden,"  was  originally  built  for 
carrying  passengers  and  light  freight,  is  132  ft.  long,  24£  ft.  beam 
with  a  draft  of  5J  ft.  and  carried  only  100  tons  on  a  draft  of  7  ft. 
She  is  a  side-wheel  steamer  with  engines  of  120  H.P.,  and  although 
the  best  that  could  be  found  at  that  time  yet  she  is  not  exactly 
adapted  to  the  work  required  of  her,  on  account  of  her  comparatively 
deep  draft  and  small  carrying  capacity,  which  rendered  it  impossible 
to  prosecute  work  the  during  periods  of  low  water. 

A  No.  9  centrifugal  drainage  pump  of  the  Andrews  patent  is 
located  on  the  main  deck  aft,  about  35  ft.  from  the  stern  post. 
Its  suction  and  discharge  openings  are  each  9-in.  in  diameter.  To 
the  suction  there  are  connected  by  a  2-way  branch  pipe  two  6-in. 
suction  pipes,  instead  of  one  9  in.  as  usual,  the  object  being  not 
only  to  work  on  both  sides  of  the  boat  simultaneously,  but  to  make 
the  necessary  handling  of  the  pipes  as  easy  and  prompt  as  possible. 

The  engine  used  to  drive  the  pump  consists  of  two  cylinders 
connected  upon  one  crank,  at  right  angles  to  one  another,  and  10  in. 
in  diameter,  each  with  a  10-in.  stroke.  Steam  b  conveyed  from 


SEA-GOING  HYDRAULIC  DREDGES  111 

the  boiler  to  the  pump  engine  through  a  3-in.  iron  pipe,  the  usual 
pressure  carried  upon  the  boiler  being  about  25  Ibs.  to  the  sq.in. 

This  pressure  develops  about  26  useful  horse  power  and  gives  a 
speed  of  about  180  revolutions  per  minute  to  the  engine  shaft.  On 
this  shaft  is  a  pulley  42  in.  in  diameter,  carrying  a  rubber  belt  12  in. 
wide,  communicating  the  power  to  the  pump  shaft  through  a  pulley 
24  in.  in  diameter,  thus  giving  the  pump  disk  and  wings  about 
315  revolutions  per  minute.  This  speed  with  the  No.  9  pump  is 
equal  to  the  work  of  raising  3000  gallons  of  clear  water  per  minute 
30  ft.  high  through  a  9-in.  vertical  pipe.  The  actual  height  raised 
above  the  water  on  the  St.  John's  bar  varies  with  the  amount  of 
sand  taken  on  board  from  10  to  11  ft.  Owing  to  the  facts  that 
the  pipes  are  50  ft.  long  with  bends,  are  in  two  branches  instead  of 
one  and  as  the  mixture  of  sand  and  water  is  heavier  and  more  impeded 
by  friction  than  clear  water,  300  revolutions  are  required  to  raise 
2500  gallons  of  sand  and  water  11  ft.  high  through  the  two  inclined 
suction  pipes  having  two  turns  each,  discharging  through  a  pipe 
having  one  turn. 

To  prevent  the  ends  of  the  suction  pipes  being  lifted  off  the 
bottom  by  the  pitching  of  the  boat,  and,  as  a  precaution  against 
accident,  a  portion  of  each  pipe  is  made  flexible,  being  composed 
of  6-in.  rubber  hose  stretched  over  a  coil  of  wire.  In  addition,  the 
ends  are  loaded  with  an  iron  frame  or  drag,  each  weighing  about 
250  Ibs.,  which  is  intended  to  move  flat  along  the  bottom  during 
the  operation  of  dredging.  To  the  under-surface  of  this  frame, 
directly  below  the  mouth  of  the  pipe,  a  number  of  teeth  or  knives 
are  attached  to  stir  up  the  sand  and  aid  its  entrance  into  the  pipes. 

Tackles  are  arranged  for  lifting  the  pipes  from  the  bottom  when 
not  dredging,  or  when  pumping  clear  water  to  discharge  the  sand 
from  the  bins. 

For  receiving  the  sand,  bins  are  located  along  the  main  deck, 
fore  and  aft,  on  each  side  of  the  steamer's  engine,  each  bin  being 
provided  with  a  sliding  gate  over  the  steamer's  side,  which  can  be 
opened  and  closed  at  pleasure.  The  bottom  of  the  bin  slopes  down- 
ward toward  the  gates.  They  are  filled  from  two  open  troughs, 
one  from  each  branch  of  the  discharge  pipe,  provided  at  suitable 
intervals  with  valves  or  gates  so  that  the  load  can  be  distributed 
to  the  bins  wherever  desired. 

Including  the  time  occupied  in  turning  the  boat  and  emptying 
the  bins,  the  least  average  result  of  an  entire  month's  work  was 


iJ 


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5 


SEA-GOING  HYDRAULIC  DREDGES 


113 


in  November,  1871,  during  which  period  .734  of  a  cu.yd.  of  sand 
per  minute  was  removed.  During  the  month  of  February,  1872, 
1.127  cu.yds.  per  minute  were  removed.  The.  greatest  quantity 
removed  on  any  one  day  was  770  cu.yds.  or  at  the  rate  of  1.26  cu.yds. 
per  minute. 

The  average  cost  of  dredging  and  dumping  the  sand  for  the  whole 


FIG.  32. — Cross-section  of  the  Dredge  "Thomas,"  showing  Central  Pit  and  Lateral 

Hoppers. 

period  of  7  months  was  53  J  cents  per  cu.yd.,  the  least  cost  during 
any  entire  week  was  19  cents  per  cu.yd.,  and  the  least  cost  for  any 
one  day  was  on  May  14,  1872,  when  770  cu.yds.  were  removed  in 
10 J  hours,  at  a  cost  of  only  13  cents  per  cu.yd.,  the  time  actually 
occupied  in  pumping  being  only  5|  hours.  With  some  modifications 
in  the  machines  the  cost  of  dredging  would  not  exceed  10  or  11 
cents  per  cu.yd.  inclusive  of  running  expenses,  wear  and  tear  of 


114  A  TREATISE  ON  DREDGES  AND   DREDGING 

machinery,  and  all  stoppages  for  repairs  and  other  contingencies. 
This  cost  would  be  greatly  reduced  in  case  the  pump  could  work 
continuously,  discharging  directly  to  the  dumping  ground  through 
either  open  troughs  or  pipes. 

The  following  description  of  the  dredge  "  Thomas,"  used  by  the 
Metropolitan  Dredging  Co.  of  New  York,  taken  from  Engineering 
News,  Vol.  XLV,  illustrates  a  type  of  hydraulic  dredge  with  two 
rows  of  parallel  hoppers  and  a  single  suction  pipe  located  in  a  well 
amidship.  See  Figs.  31  and  32. 

This  dredge  is  of  7000  tons  displacement,  300  ft.  long,  52  ft. 
6  in.  beam,  25  ft.  molded  depth,  and  has  a  hopper  capacity  of  2800 
cu.yds.  of  material  and  a  speed  of  10  knots.  As  will  be  seen  from 
the  general  plans,  the  hulls  are  of  steel,  and  are  provided  with  two 
decks.  For  about  125  ft.  amidships  the  hull  space  below  the  main 
deck  is  taken  up  by  a  row  of  hoppers  on  each  side,  there  being  six 
hoppers  in  each  row,  two  being  22J  ft.  long  by  18  ft.  wide,  and  four 
being  20  ft.  long  by  18  ft.  wide.  The  forward  portion  of  the  space 
between  the  two  rows  of  hoppers  is  occupied  by  the  well  for  the 
suction  pipe.  Aft  of  the  hoppers  the  hull  space  below  the  main 
deck,  is  given  up  to  the  main  engine  and  boiler-room,  propelling 
machinery  and  steering  gear,  and  forward  the  corresponding 
space  is  devoted  to  the  pump  and  pumping  engines.  The  space 
between  the  main  and  upper  decks  is  devoted  chiefly  to  the  quarters 
for  the  officers  and  men.  The  upper  deck  carries  the  derricks, 
windlasses  and  usual  above-deck  structures  of  a  sea-going  vessel. 
Taking  up  the  description  of  the  various  parts  named  in  more  detail, 
we  have  first  to  consider  the  dredging  machinery  and  hoppers. 

The  space  forward  of -the  hoppers,  which  is  devoted  to  the  dredging 
machinery,  extends  the  full  width  of  the  vessel  and  for  50  ft.  fore 
and  aft.  The  main  centrifugal  pump  is  located  in  the  center  close 
to  the  forward  end  of  the  suction  pipe  well.  It  is  a  48-in.  pump 
built  by  the  Morris  Machine  Works,  of  Bald  wins  ville,  N.  Y.,  and 
has  two  side  pipes  to  the  suction  pipe  and  two  discharge  openings 
connected  with  separate  discharge  pipes  leading  to  the  two  rows  of 
hoppers,  as  shown  by  the  drawings.  This  pump  is  operated  by  two 
tandem,  compound  17x30x36-in.  stroke  cylinder  engines,  exhaust- 
ing into  condensers.  The  pump  has  a  guaranteed  capacity  of  75,000 
gallons  of  water  per  minute,  and  will  operate  under  a  resistance 
equal  to  about  40  ft.  head  of  water.  The  centrifugal  pumping 
engines  are  placed  forward  of  the  pump,  and  forward  of  them  is  a 


SEA-GOING  HYDRAULIC  DREDGES  115 

large  compound  condensing  duplex  pump  made  by  the  Stilwell- 
Bierce  &  Smith-Vailc  Co.,  of  Dayton,  O.,  for  the  water  jets  on  the 
section  drag  and  in  the  discharge  valves  of  the  hoppers.  This  pump 
has  18X30  in.  steam  and  24x24  in.  water  cylinders.  Another  duplex 
pump,  with  6X18  in.  plungers,  capable  of  pumping  against  a  pressure 

1  of  1000  Ibs.  per  sq.in.,  is  employed  for  operating  the  hydraulic 
cylinders  by  which  the  discharge  valves  in  the  hoppers  are  actuated 
and  also  for  operating  the  hoists  for  raising  the  suction  pipe. 

The  hoppers  'have  rectangular  bodies  terminating  in  frustums 
of  rectangular  inverted  pyramids  at  the  bottoms.  The  discharge 
outlet  in  the  bottom  of  each  hopper  is  4  ft.  in  diameter,  and  is  closed 
by  a  trunk  valve  of  the  same  diameter  which  extends  up  through 
the  hopper  and  is  raised  and  lowered  by  a  12-in.  hydraulic  cylinder. 
In  operation  this  trunk  valve  is  raised  about  3  ft.  to  allow  the  contents 
\of  the  hopper  to  discharge.  To  facilitate  the  discharge  of  these 
contents  and  to  loosen  them  up  so  that  the  trunk  valve  may  be 
easily  hoisted,  water  is  forced  through  the  jets  in  the  discharge 
valve  by  the  pump  previously  mentioned.  When  the  discharge 
is  completed  the  centrifugal  pump  is  started,  forcing  clear  water 
through  the  discharge  pipes  and  into  perforated  flushing  pipes 
located  in  each  hopper  around  the  walls  at  a  point  where  the  vertical 

'  and  inclined  sides  join.  -This  operation  cleanses  the  discharge 
pipes  and  the  hoppers  of  all  the  undislodged  contents. 

The  main  boiler  and  engine-room  contains  two  boilers  14  ft. 
in  diameter  and  11  ft.  10  in.  long,  operating  under  180  Ibs.  steam 
pressure,  and  between  the  main  boilers  there  is  also  a  7^X9  ft.  donkey 
boiler.  Aft  of  the  boilers  are  located  two  inverted-cylinder,  direct- 
acting,  triple-expansion  engines,  with  18-,  25-  and  48-in.  cylinders, 
with  30-in.  stroke.  The  high-pressure  and  intermediate  cylinders 
have  piston  valves,  and  the  low  pressure  cylinder  has  slide  valves. 
These  engines  drive  twin  screws. 

The  operation  of  the  dredge  is  as  follows:  The  suction  tube  is 
lowered  to  the  bottom  and  the  air  exhausted  from  the  centrifugal 
pump  by  a  4-in.  injector.  When  the  pump  is  charged  the  pumping 
engines  are  started,  rilling  the  tanks  with  water.  The  suction  pipe 
having  fed  itself  into  the  bottom  to  a  sufficient  depth,  the  dredge 
is  moved  ahead  at  a  speed  of  about  25  or  30  ft.  per  minute,  until 
the  hoppers  are  filled  with  dredgings.  To  loosen  the  material  so 
that  the  suction  can  secure  it,  the  water  jets  previously  noted  are 
kept  in  operation.  When  the  hoppers  are  filled  the  suction  pipe  is 


116  A  TREATISE  ON   DREDGES   AND   DREDGING 

raised,  and  the  dredge  proceeds  to  sea,  where  it  discharges  its  load 
by  performing  the  series  of  operations  previously  described. 

The  fittings  of  the  dredge  are  unusually  complete  throughout, 
and  a  particular  attempt  has  been  made  to  provide  comfortable 
quarters  for  the  officers  and  crew.  These  quarters,  together  with 
the  messrooms,  pantries,  etc.,  are  located  above  the  main  deck, 
as  shown  by  the  drawings,  which  also  show  in  sufficient  detail  the 
above-deck  structure  and  rigging. 

The  following  description  of  a  hydraulic  dredge  with  two  suction 
pipes  and  a  central  hopper  is  taken  from  Engineering,  November 
22,  1901. 

The  lower  reach  of  the  Seine,  from  Rouen  to  the  open  sea,  had, 
until  recently,  been  practically  unused  for  maritime  service, 
although  it  might  have  been  made  a  first-class  channel  for  commercial 
purposes.  Navigation,  as  far  as  Rouen,  was  carried  out  under 
very  great  difficulties,  owing  to  the  varying  nature  of  the  water 
discharge  and  the  changing  depths.  Up  till  1848,  of  the  78  miles 
which  separate  Rouen  from  the  sea,  37,  at  least,  formed  an  estuary 
of  exceedingly  great  width,  useless  in  the  point  of  view  of  navigation, 
the  fairway  being  a  shallow  and  very  changeable  one,  in  the  midst 
of  shifting  sandbanks  and  mud.  In  the  period  from  1848  to  1866  a 
series  of  longitudinal  dykes  were  built  on  both  banks,  the  total  devel- 
oped length  of  which  rapidly  extended  to  over  40  miles;  these 
gave  good  results  in  the  sense  that  they  deepened  the  channel  at 
many  places.  From  1866  to  1885  no  new  work  was  carried  out, 
and  the  maintenance  in  good  state  of  repair  of  the  dykes  previously 
built — with  unsuitable  material — was  very  laborious.  Since  1885 
attempts  have  been  made  to  improve  the  conditions  of  navigation 
up-stream  from  the  Risle  River,  and  the  conditions  of  the  estuary 
proper.  The  object  is  to  regulate  the  distance  between  the  opposite 
banks  in  such  a  way  that  the  body  of  water  available  is  the  largest 
possible,  dredging  being  resorted  to  in  order  to  improve  the  flow 
and  deepen  the  channel.  In  1895  a  powerful  bucket  dredge  was 
put  in  service;  this  was  found  very  efficient,  in  that  it  easily  reduced 
to  3  ft.  under  the  zero  of  the  charts,  beds  that  were  formerly  above 
zero.  As  soon,  however,  as  an  experimental  suction  dredge  had 
been  tried  and  found  to  give  excellent  results,  the  Seine  Board  of 
Works  ordered  three  powerful  ones  of  this  system  from  the  Societe 
des  Anciens  Etablissements  Sat  re,  of  Lyons,  Aries,  and  Rouen. 

There  being  very  often  rough  weather  on  the   Lower  Seine, 


SEA-GOING  HYDRAULIC  DREDGES  117 

*•'  9' 

and  as  there  could  be  no  question  of  putting  the  dredges  in 
shelter  when  not  in  actual  work,  they  had  to  be  built  seaworthy 
throughout.  They,  in  fact,  traveled  under  their  own  steam  from 
Marseilles  to  Havre,  having  been  built  at  Aries,  in  the  south 
of  France,  and  behaved  perfectly  well  in  the  crossing.  The 
central  portion  of  the  dredge  in  question  is  given  in  Fig.  33. 
The  hull  is  divided  into  compartments  by  eight  watertight 
bulkheads.  The  first  compartment  is  the  forepeak,  used  as  a 
hold;  the  second  one  is  the  crew  space,  with  berths  for  eight 
men.  The  next  compartment  contains  the  officers'  cabins  and 
one  cabin  for  the  Fonts  and  Chaussees  engineer,  who  has  charge 
of  inspecting  and  supervising  the  work  done.  In  the  foUowing 
compartments  are  the  sand  and  mud  wells,  the  normal  capacity 
of  which  is  17,658  cu.ft.,  the  maximum  capacity  being  20,483  cu.ft., 
when  extension  tops  are  put  round  the  openings  of  the  hoppers, 
which  is  possible  in  fine  weather.  The  wells  are  seven  in  number, 
fitted  with  two  pairs  of  doors  or  sluices.  The  next  compartment 
forms  the  engine-room,  and  also  contains  the  dredge  pumps;  the 
one  next  to  it  is  the  stokehold,  with  coal  bunkers,  the  last  one  being 
the  chain  locker. 

There  are  in  each  dredge  two  vertical  compound  engines,  capable 
of  developing  together  a  total  of  540  indicated  horse-power  at  150 
revolutions.  This  type  of  engine  has  been  built  in  large  numbers 
by  Messrs.  Satre  for  various  purposes.  Their  principal  dimensions 
are  the  following: 

Diameter  of  high-pressure  cylinder 0.440  m.  (17^  in.) 

Diameter  of  low-pressure  cylinder 0.800  m.  (3l|  in.) 

Stroke 0.450  m.  (17ft  in.) 

They  are  surface-condensing;  the  condenser  is  placed  horizontally, 
and  forms  part  of  the  engine  frame.  The  valves  are  easily  accessible 
for  inspection  and  maintenance  in  good  working  order.  The  engines 
are  so  arranged  that  they  can  readily  be  made  to  drive,  together  or 
separately,  both  the  propellers  or  the  pumps.  The  boilers  are 
Belleville  boilers,  fitted  with  economizers  of  2154  sq.ft.  heating 
surface,  with  two  donkey  pumps,  and  with  an  air  compressor  of 
8830  cu.ft.  A  fresh-water  tank  can  supply  the  boilers  during  a 
continuous  run  of  75  hours;  suitable  apparatus  are  provided  for 
filtering  the  feed-water  taken  from  the  drain-pipes  and  condensers. 
Each  dredge  is  driven  by  two  propellers  worked  from  the  engine 


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SEA-GOING  HYDRAULIC  DREDGES  119 

shafts  through  couplings.  The  propellers  are  independent  one  of 
the  other,  and  can  turn  inversely,  this  being  rather  a  novel  feature 
for  this  kind  of  craft. 

The  dredging  device  consists  of  two  centrifugal  pumps  worked 
from  the  main  engine.  The  pump  shells  are  cast  in  one  piece,  and 
provided  with  manholes  for  removing  all  obstructions  when  necessary. 
The  suction  turbines  have  four  blades,  and  contain  a  special  arrange- 
ment which  prevents  the  sand  from  penetrating  between  the  blades 
and  the  inside  walls  of  the  pump  body.  The  door-pieces  on  the  front 
part  of  the  pumps  carry  the  suction  necks,  which  are  connected, 
through  an  elbow  that  runs  through  the  deck  and  a  horizontal 
conduit,  to  another  neck;  the  latter  is  fitted  to  the  suction  pipe 
through  another  elbow,  .a  flexible  length  of  tubing  and  a  Hooke's 
joint.  The  suction  pipe  can  draw  sand  from  a  depth  of  43  ft.  below 
water  level,  and  can  work  even  during  a  rolling  swell  of  91  in.  The 
joint  with  the  suction  pipe  being  level  with  the  deck,  all  work  of  main- 
tenance and  repair  is  easily  carried  out.  The  discharge  from  the 
pumps  is  effected  through  shoots,  each  with  seven  openings,  provided 
with  sluice  doors  to  regulate  the  delivery  on  the  dredge.  Hoppers 
of  perforated  plates  are  provided  in  the  sand  wells. 

Double  steam  winches  are  placed  on  deck  at  both  ends;  these 
are  supplied  with  steam  from  an  auxiliary  boiler.  Another  steam 
winch  serves  to  work  the  sluice  valves  and  the  suction  pipe.  The 
auxiliary  boiler  in  question  is  multitubular,  and  supplies  not  only 
the  winches,  but  also  gives  steam  for  the  electric  lighting  of  the 
boat  and  for  heating  the  various  berths.  The  electric-lighting 
equipment  serves  to  facilitate  night  work;  three  arc  lamps  of  1000 
candle-power  each  are  provided  on  deck  for  this  purpose. 

These  dredges  give  full  satisfaction.  They  were  to  draw  each 
17,658  cu.ft.  in  50  minutes;  their  traveling  speed  in  a  rolling  swell 
of  15  in.  was  specified  to  be  8  knots,  with  a  coal  consumption  of 
1.87  Ibs.  per  indicated  horse-power  per  hour.  During  the  tests 
the  wells  were  filled  in  38  minutes;  the  speed  reached  was  8J  knots, 
with  a;  coal  consumption  of  1.70  Ibs.  only. 


CHAPTER  XV 

HYDRAULIC    DREDGES    FOR    CHANNELS    AND    RIVER 
IMPROVEMENTS 

THE  hydraulic  dredges  used  in  the  improvements  of  harbors  and 
rivers  usually  discharge  the  dredged  materials  onto  the  nearby 
lands  by  means  of  long  floating  discharge  pipe.  These  dredges, 


FIG.  34.— Dredge  "J.  Israel  Tarte." 

according  to  Mr.  Robinson,  can  be  divided  into  three  groups, 
as  follows: 

1st.   Lateral  feeding. 

2d.   Forward  feeding. 

3d.   Radial  feeding. 

Lateral  Feeding.  Possibly  the  only  lateral-feeding  hydraulic 
dredge  is  the  "  J.  Israel  Tarte  "  designed  by  Mr.  A.  W.  Robinson  for 
the  improvement  of  the  St.  Lawrence  River  ship  channel  and 
described  by  himself  in  a  paper  read  before  the  Canadian  Society 
of  Civil  Engineers. 

The  hull  of  the  dredges,  Fig.  34  and  35,  is  of  steel  and  is  160  ft. 
long,  42  ft.  beam,  12  ft.  6  in.  deep.  The  plating  is  J  in.  thick  on  the 
bottom  and  f  in.  on  the  sides  with  tfc-in.  deck.  The  hull  is  rounded 

120 


HYDRAULIC  DREDGES  FOR  CHANNELS 


121 


at  the  bilges,  but  it  is  rectangular  in  plan  with  rounded  ends  in  side 
view.  There  is  a  central  opening,  or  well,  through  which  the  suction 
pipe  works.  This  well  is  8  ft.  wide  except  at  the  forward  end,  where 
it  is  10  ft.  wide  to  admit  the  cutter,  and  it  is  of  sufficient  length  to 
receive  the  pipe.  The  suction  pipe  is  formed  of  a  rectangular  steel 
box  girder  of  great  strength,  and  having  its  lower  horizontal  web 
extended  in  width  so  as  to  fit  between  the  sides  of  the  well.  The 
flanges  of  this  horizontal  girder  are  formed  of  two  angle  irons  5x5Xi 
in.  covered  with  a  plate  12x|  in.,  which  bear  against  the  sides  of  the 


FIG.  35.— Plan  and  Longitudinal  Section  of  the  Dredge  "  J.  Israel  Tarte." 

well.  This  is  for  the  purpose  of  withstanding  the  great  lateral  strain 
due  to  feeding  the  dredge  sideways  and  with  the  cutter  in  contact 
with  the  bottom.  The  suction  pipe  is  hinged  to  the  hull  at  the 
deck  by  means  of  massive  steel  hinged  castings,  and  a  steel  bulkhead 
extends  the  entire  width  of  the  hull  at  this  point.  The  sides  of  the 
hull  are  extended  above  the  deck  to  form  a  solid  steel  bulwark 
entirely  around  the  dredge,  the  hand-rail  being  formed  of  an  8-in. 
bulb  angle  finished  on  the 'outside  with  2J  in.  half  round.  These 
bulwarks  form  a  protection  against  the  seas  which  sometimes  break 
over  the  dredge. 


122 


A  TREATISE  ON   DREDGES   AND   DREDGING 


The  suction  pipe  is  suspended  from  a  double  steel  A  frame  over 
the  forward  end  of  the  well,  and  the  lifting  winch  for  raising  and 
lowering  the  suction  pipe  is  carried  on  top  of  this  frame. 

The  main  engines  are  of  the  triple-expansion  marine  type,  having 
cylinders  20,  31  and  50  in.  in  diameter  with  25-in.  strokes.  They 
are  adapted  to  run  at  150  revolutions  per  minute. 

The  material  is  excavated  by  an  improved  rotary  cutter  (see 


FIG.  36.— Floating  Discharge  Pipe  of  the  .Dredge  "J.  Israel  Tarte." 

Fig.  26) ,  9  ft.  6  in.  diameter  by  9  ft.  long,  the  weight  of  which  is 
10  tons.  It  is  formed  of  steel  blades  with  especially  designed  clear- 
ance spaces  between  them,  so  as  to  avoid  clogging  with  the  material, 
and  the  suction  pipe  and  passages  through  the  pump  are  made 
very  large  for  the  same  reason.  The  cutter  is  driven  by  a  pair  of 
engines  placed  on  top  of  the  suction  pipe  at  the  upper  end. 
These  engines  are  of  the  double  tandem  type  of  300  I.H.P.; 
the  gearing  and  power  transmission  for  these  engines  is  of  exceptional 
strength  and  capable  at  all  times  of  encountering  immovable 


HYDRAULIC  DREDGES  FOR  CHANNELS  123 

resistances  with  full  head  of  steam  on  the  engines  without  risk  of 
breakage.  The  main  gearing  driving  the  cutter  is  of  cast  steel 
5  in.  pitch  and  5  in.  face. 

Steam  is  furnished  by  four  boilers,  having  collectively^  8500 
sq.ft.  of  heating  surface,  and  adapted  for  working  pressures  of 
160  Ibs.  There  is  coal  bunker  capacity  of  200  tons. 

The  main  pump  is  of  the  centrifugal  type,  having  cast-steel 
runners  of  inclosed  type  and  heavy  cast-iron  shell.  The  blades  of 
the  runner  and  the  heads  of  the  pump  are  protected  by  renewable 
steel  wearing  plates  in  the  shell.  This  shell  is  exceedingly  heavy, 
so  that  it  can  stand  a  considerable  amount  of  wear  before  it  begins 
to  fail,  and  it  is  also  so  designed  that  the  stream  of  material  issuing 
from  the  runner  does  not  impinge  to  any  extent  upon  it  at  any  one 
point. 

The  entire  operations  of  the  dredge  are  controlled  from  the 
pilot-house  on  the  upper  deck.  Here  are  located  the  levers  for 
both  the  bow  and  stern  anchorage  winches  and  the  lifting  winch  for 
the  suction  pipes;  also  a  system  of  bells  and  signals  to  the  engine 
room.  The  pilot-house  is  so  placed  that  the  operator  has  an  unob- 
structed view  up  and  down  the  river;  also  of  the  entire  discharge- 
pipe  (see  Fig.  36). 

The  dredge  is  fitted  with  complete  quarters  for  a  double  crew 
of  36  men,  or  18  men  on  each  shift.  The  dredge  works  continuously 
from  Sunday  night  till  Saturday  night,  without  stopping  except 
when  necessary.  The  dredge  is  attended  by  a  powerful  light -draft 
twin-screw  tug.  The  principal  duty  of  this  tug  is  to  fleet  the  anchors 
as  the  dredge  moves  ahead.  The  side  lines  of  the  channel  to  be 
made  are  marked  at  night  by  temporary  range  lights. 

The  efficiency  of  the  dredge  "  J.  Israel  Tarte  "  is  estimated  at 
600,000  cu.yds.  per  month,  although  for  short  periods  it  has  worked 
at  the  rate  of  2600  cu.yds,  per  hour.  The  average  cost  per  cu.yd. 
for  the  year  is  about  If  cents.  This  dredge  was  built  by  the  Pol§on 
Iron  Works  of  Toronto,  Can.,  at  a  cost  of  $163,800,  excluding  the 
discharge  pipe  and  the  winches,  which  were  not  designed  wThen  the 
contract  was  placed. 

Forward  Feeding.  The  second  group  of  the  hydraulic  dredges 
employed  in  the  improvements  of  channels  and  rivers  are  those 
provided  with  a  forward  feeder  and  extensively  used  on  the  Mississ- 
ippi River.  The  following  description  of  the  "  Delta  "  taken  from  a 
paper  by  Mr.  Ockerson,  will  serve  to  illustrate  this  type  of  dredge. 


124  A  TREATISE   ON  DREDGES  AND   DREDGING 

The  hull  is  of  steel,  175  ft,  long,  38  ft.  wide,  and  8}  ft.  deep. 

The  dredging  pump  is  different  from  any  other  in  the  shape  of  the 
casing  and  the  runner.  The  runner  has  five  blades  22  in.  wide, 
and  is  7  ft.  in  diameter.  The  edges  run  close  to  the  casing,  but  the 
runner  is  not  concentric  with  the  casing,  hence  the  outer  ends  of 
the  arms  are  nearer  one  side  of  the  casing  than  the  other,  the  widest 
space  being  at  the  bottom,  and  the  space  being  nearly  cut  off  by  a 
projection  in  the  casing  at  the  upper  side  of  the  discharge  opening. 
The  axis  of  the  pump  is  parallel  to  the  axis  of  the  boat  and  lies  over 
the  center  line  of  the  same.  The  shaft  has  one  long  bearing  through 
the  aft  side  of  the  casting,  and  is  provided  with  water  bushing  under 
pressure  to  keep  the  sand  out  of  the  bearing.  The  sand  pump  is 
driven  by  a  vertical,  inverted,  two-crank,  compound-condensing 
engine,  with  cylinders  22  and  48  in.  diameter  and  24-in.  stroke.  It 
is  fitted  with  a  piston  and  slide  valve  and  has  an  adjustable  cut  off 
for  the  piston  valve.  This  engine  was  designed  to  develop  800  H.P. 
at  140  revolutions  per  minute,  with  a  boiler  pressure  at  160  Ibs.  and 
a  vacuum  of  25  in. 

The  engine  which  drives  the  cutters  is  horizontal,  two  cylinder 
and  non-reversible,  attached  to  a  sliding  steel  frame,  which  moves 
back  and  forth  in  guides  as  the  cutter  is  raised  or  lowered.  This  is 
necessary  because  the  shaft  which  drives  the  sprocket  chain  is  not 
in  the  axis  of  motion  on  which  the  suction  and  cutter  revolve. 
The  whole  engine,  with  its  frame,  follows  the  motion  of  the  shaft, 
so  that  the  gear  and  pinion  are  always  engaged.  To  admit  of  this 
motion,  the  steam  pipes  are  provided  with  slip  joints.  The  cylinders 
of  this  engine  are  12^  in.  in  diameter  and  15-in.  stroke,  with  the  loco- 
motive type  of  slide  valve. 

There  are  two  winding  drums  located  forward  of  the  sand  pump, 
one  on  the  starboard  and  the  other  on  the  port  side  of  the  hull. 
These  drums  are  provided  with  clutches  and  brakes,  and  are  driven 
by  two  independent  double-cylinder,  horizontal  engines  with  cylinders 
10X12  in. 

The  ladder  hoist  for  raising  and  lowering  the  suction,  and  the 
spud  hoist  for  raising  the  spud,  each  has  drums  24x24  in.  The 
cables  from  these  drums  lead  to  the  roof  and  thence  out  through 
sheaves  to  the  ladder  and  spud.  These  drums  are  operated  by  the 
same  engines  that  operate  the  winding  drums. 

Steam  is  supplied  by  four  Heine  safety  water-tube  boilers  rated 
at  250  H.P.  each. 


HYDRAULIC  DREDGES  FOR  CHANNELS  125 

• 

The  intake  of  the  sand  pump  is  from  one  pipe  34  in.  in  diameter, 
entering  in  the  axis  of  the  pump  at  the  forward  side  of  the  casing. 
This  single  pipe  runs  25  ft.  to  the  forward  bulkhead  and  there 
branches  into  two  pipes  each  24  J  in.  in  diameter,  which  separate 
and  pass  through  the  bow  of  the  boat  below  the  water-line  9  ft. 
apart.  These  two  pipes  turn  to  the  right  and  left  along  the  outside 
of  the  bow  and  then  turn  forward  again  and  each  branch  separates 
into  two  suction  heads.  The  whole  is  framed  together  so  that  the 
four  pipes,  suction  heads  and  cutters  are  raised  and  lowered  together 
as  one  piece.  Instead  of  a  radial  slipjoint  for  the  suction  pipes,  as 
used  on  the  other  dredges,  there  is  a  vertical  flanged  joint  in  the 
horizontal  part  of  each  pipe  next  to  the  bow,  and  the  revolving 
pins  that  sustain  the  weight  of  the  aft  end  of  the  suction  are  placed 
in  the  prolonged  axes  of  these  pipes. 

The  cutter  for  loosening  up  the  material  is  placed  at  the  outer 
end  of  the  suction  head..  It  has  22  cast-steel  wheel  cutters,  each 
having  four  blades  mounted  on  a  steel  shaft  6J  in.  square.  This 
shaft  is  driven  by  the  cutter  engine  by  means  of  two  steel  sprocket 
chains,  at  a  rate  of  about  eight  revolutions  per  minute. 

The  floating  discharge  pipe  is  1000  ft.  long  with  the  usual  rubber 
couplings  at  intervals  of  50  ft.  There  are  pontoon  floats  on  each 
side  of  this  pipe  U-shaped  in  section,  with  the  flat  side  closed,  and 
they  sustain  the  pipes  in  yokes  which  are  firmly  attached  to  the 
floats.  There  is  a  baffle  plate  at  the  end  of  the  pipe  line.  The  dredge 
is  provided  with  sixteen  hydraulic  piles,  six  of  which  are  10  in.  in 
diameter  and  38  ft.  long,  and  ten  are  6  in.  in  diameter  and  25  ft. 
long. 

This  dredge  was  constructed  under  contract*  with  the  New  York 
Dredging  Co.,  which  sublet  the  construction  of  different  parts  to 
various  manufacturers  and  builders  of  machinery.  The  contract 
price  for  this  dredge  was  $124,940.  The  maximum  efficiency  of 
this  dredge  was  found  to  be  3212  cu.yds.  of  sand  per  hour  while 
the  minimum  was  928  cu.yds.  per  hour. 

Radial  Feeding.  The  last  group  of  the  hydraulic  dredges  used 
in  the  channel  and  river  improvements  are  those  with  radial  feeding 
and  are  illustrated  here  by  the  description  of  the  dredge  "  King 
Edward  VII,1'  slightly  condensed  from  a  paper  by  Mr.  A.  W. 
Robinson,  delivered  before  the  Canadian  Society  of  Civil  Engineers. 

The  dredge  "King  Edward  VII."  is  anchored  by  spuds  and 
has  a  radial  feed,  the  cutter  describing  an  arc  of  a  circle  about  the 


HYDRAULIC  DREDGES  FOR  CHANNELS 


127 


spud  as  a  center,  and  the  material  is  principally  deposited  on  shore 
or  at  a  distance  through  the  floating  discharge  pipe. 

Referring  to  the  illustrations,  Fig.  37  is  a  deck  plan  and  longi- 
tudinal section  of  the  dredge  by  which  tlie  general  arrangement 
of  the  machinery,  crew's  quarters,  etc.,  may  be  seen.  Fig.  38  shows 
cross-section  at  the  pump.  Fig.  39  shows  the  dredge  with  cutter 
raised. 

The  hull  of  the  dredge  is  32  ft.  wide,  125  ft.  long  and  7  ft.  6  in. 
deep.  It  is  built  square-ended  at  bow  and  stern,  with  corners  well 
rounded  and  a  rake  on  the  under  body  fore  and  aft  in  order  to  make 


FIG.  38. — Cross-section  of  the  Dredge  "King  Edward  VII." 

it  fairly  easy  to  propel.  By  referring  to  the  cross-section  it  will  be 
seen  that  the  bilges  are  rounded  and  that  the  frame  of  the  vessel 
is  built  of  steel,  while  the  plank  and  sheathing  are  of  wood.  By 
this  construction  great  strength  is  obtained,  the  steel  frames  being 
practically  indestructible,  while  the  planking  can  be  renewed  at 
any  time  when  necessary  from  injury  or  decay.  This  form  of  con- 
struction was  also  especially  suitable  for  erection  on  the  Pacific 
coast,  as  the  entire  frame  of  the  hull  could  be  fitted  and  erected 
at  the  works  where  built,  leaving  only  the  planking  to  be  purchased 
and  put  on  at  place  of  erection.  The  hull  is  stiffened  by  two  additional 
steel  trusses  extending  the  entire  length.  These  trusses  are  15  ft. 


128 


A  TREATISE  ON   DREDGES   AND   DREDGING 


deep  and  serve  to  strengthen  and  carry  the  weight  of  the  upper 
deckhouses.  They  also  sustain  the  weight  and  thrust  of  the  front 
A  frame  and  furnish  the  necessary  support  for  the  wheel  beams  at 
the  aft  end.  The  hull  is  further  stiffened  by  four  transverse  water- 
tight steel  bulkheads. 

The  engines  are  of  the  triple-expansion  marine  type  of  500  H.P. 
The  engines  and  pump  as  they  appear  in  the  engine  room  are  illus- 
trated in  Fig.  37.  There  are  no  special  features  about  this  engine 


I 


FIG.  39.— Dredge  "King  Edward  VII." 

which  call  for  detailed  desciiption.  It  is  simply  a  first-class  marine 
engine  without  the  link  motion.  The  work  of  driving  a  centrifugal 
pump  is  somewhat  analogous  to  that  of  driving  a  screw  propeller, 
and  therefore  the  type  of  marine  engine  is  well  adapted  to  the  pur- 
pose. There  are,  of  course,  many  little  practical  details  concerning 
the  manner  of  attachment  of  the  pump  and  providing  for  the  special 
wear  and  thrust  that  occur  in  the  pump  that  are  different  from 
marine  practice. 

The  dredging  pump  itself  is  of  the  centrifugal  type,  of  a  pattern 


HYDRAULIC  DREDGES  FOR  CHANNELS        129 

which  has  been  arrived  at  through  the  correction  of  defects  of  earlier 
designs.  The  pump  has  a  cast-iron  shell  with  cast-steel  runner  and 
blades.  The  suction  and  discharge  pipes  are  both  20  in.  diameter. 
The  blades  of  the  pump  runner  are  faced  with  renewable  steel 
blades  at  points  of  greatest  wear  and  the  pump  is  so  designed  that 
it  can  be  readily  taken  apart  and  the  pump  runner  removed  with- 
out taking  down  the  pump  shell  or  discharge-pipe  connections. 
The  internal  passageways  of  the  pump  are  of  large  area,  so  as  to 
pass  freely  any  stones  or  solid  bodies  that  may  enter  through  the 
openings  of  the  suction  head  without  injury  or  liability  to  choke  it. 
It  will  readily  be  seen  that  if  the  passages  of  the  pump  were  of 
smaller  size  than  the  openings  through  the  cutter  head  that  stones 
or  other  obstructions  might  lodge  in  the  pump,  but  by  the  foregoing 
precaution  this  liability  is  obviated. 

By  referring  to  the  plan  it  will  be  seen  that  the  entire  suction 
pipe  projects  in  front  of  the  dredge  and  swings  thereupon,  its  lateral 
movement  being  accomplished  by  means  of  a  block  and  tackle  on 
each  side,  the  hauling  parts  of  which  are  carried  to  the  drums  of 
the  auxiliary  engines.  The  suction  pipe  has  a  universal  movement 
on  the  hull  so  that  it  can  raise  and  lower  as  well  as  swing.  This 
movement  is  provided  for  by  a  section  of  rubber  suction  hose  where 
it  passes  over  the  deck,  the  suction  pipe  being  attached  by  hinges 
to  a  revolving  base  plate  on  the  bow  of  the  dredge. 

The  material  is  excavated  by  means  of  a  rotary  cutter  head, 
which  is  formed  of  a  cast-steel  hollow  shell  and  removable  cast-steel 
blades.  These  blades  are  arranged  on  a  spiral  and  so  as  to  give  the 
maximum  effect  with  the  least  liability  of  choking.  The  action 
of  the  cutter  is  such  that  the  blades  slice  off  or  excavate  the  material 
and  feed  it  into  the  interior  of  the  shell  through  the  openings, 
whence  it  is  removed  by  the  pump  suction.  The  cutter  head  with 
its  shaft,  gearing  and  all  connections  are  of  ample  strength  to  stall 
the  engines  which  drive  them.  Thus,  in  case  of  an  immovable 
resistance  being  encountered,  nothing  worse  can  happen  than  the 
stoppage  of  the  engines,  and  by  slacking  off  the  feed  of  the  cutter 
a  little,  they  are  enabled  to  proceed  and  try  again.  It  is  worthy 
of  note  that  since  this  dredge  has  been  in  commission  she  has  worked 
in  all  kinds  of  material,  including  roots,  stumps,  hardpan  and  stones, 
and  that  no  breakage  or  injury  has  occurred  to  the  cutter  head  or  its 
driving  gear. 

It  will  be  observed  that  the  suction  pipe  when  swinging  on  the 


130  A  TREATISE  ON  DREDGES   AND   DREDGING 

hull  will  make  a  cut  about  equal  to  the  width  of  the  hull,  while  the 
latter  is  anchored  by  its  two  spuds.  When  it  is  desired  to  make 
a  wide  cut  the  suction  pipe  is  secured  in  its  mid-position  and  the 
swinging  lines  are  carried  out  on  each  side  to  a  shore  anchorage,  and 
the  entire  dredge  swings  on  its  stern  spud,  thus  making  a  cut  from 
150  to  175  ft.  wide  at  one  time.  The  spuds  are  oscillating  so  as  to 
permit  the  dredge  to  move  up  without  drifting  out  of  position, 
and  when  the  move  is  made,  they  are  lifted  and  dropped  again  in 
vertical  position  and  the  work  proceeds.  The  moving  up  is  accom- 
plished by  giving  a  turn  or  two  to  the  stern  wheel  by  the  propelling 
engines. 

The  auxiliary  engines  are  on  the  forward  deck.  These  are  for  the 
purpose  of  working  the  swinging  lines  and  also  hoisting  the  forward 
spud.  The  operator  of  the  dredge  controls  all  the  movements  of 
feeding  and  moving  up  through  the  medium  of  these  engines  and 
by  bell  signals  to  the  engineer.  The  entire  dredge  is  therefore  under 
the  control  of  one  man. 

The  boilers,  as  shown  on  the  plan,  are  of  the  Heine  water-tube 
type.  This  type  of  boiler  is  not,  strictly  speaking,  a  marine  boiler, 
although  it  has  answered  very  well  for  this  class  of  work.  They 
are  of  the  usual  land  type,  cased  in  steel,  lined  with  firebrick.  The 
boilers  are  designed  for  a  working  pressure  of  200  Ibs.  per  sq.in., 
and  have  an  excess  of  capacity  to  provide  steam  for  all  machinery, 
'and  in  case  of  necessity  the  dredge  can  work  at  fair  capacity,  with 
only  one  boiler  in  commission,  while  the  other  is  under  repairs. 

In  the  engine  room  the  usual  auxiliaries  are  found,  such  as  surface 
condenser,  air  pump,  centrifugal  circulating  pump  and  independent 
feed  and  fire  pumps.  These  are  all  of  ample  size  and  conveniently 
arranged  for  ease  of  access  and  repairs. 

The  propelling  engines  are  of  the  stern-wheel  type,  so  often  seen 
on  the  western  rivers.  They  are  of  the  direct-acting  long-stroke 
horizontal  type  and  have  cylinders  16  in.  diameter  by  6  ft.  stroke. 
They  are  mounted  on  a  steel  frame  and  have  answered  the  purpose 
very  well. 

It  will  be  seen  that  the  whole  of  the  main  deck  is  occupied  with 
machinery  and  the  whole  of  the  upper  deck  is  given  up  to  quarters 
for  the  officers  and  crew. 

The  performance  of  the  dredge  has  been  quite  satisfactory, 
although  no  very  large  or  continuous  outputs  have  been  made, 
owing  to  the  fact  that  the  work  to  be  done  has  been  principally 


HYDRAULIC  DREDGES  FOR  CHANNELS  131 

small  jobs  at  different  points,  and  in  various  kinds  of  material, 
some  of  which  has  been  of  a  very  difficult  nature.  The  capacity 
of  500  cu.yds.  per  hour  has  frequently  been  obtained,  and,  under 
favorable  conditions,  the  output,  for  short  periods  of  time,  has 
approached  1000  cu.yds.,  but  the  average,  owing  to  the  reasons 
already  stated,  has  been  much  less  than  this. 

To  convey  the  dredged  material  ashore  lengths  of  sheet  steel 
pipe  are  used  laid  on  the  ground  and  blocked  up  where  necessary. 
These  pipes  are  simply  slipped  into  one  another  like  stovepipes,  and 
no  special  arrangements  for  keeping  them  tight.  The  gravel  and  clay 
in  the  interior  soon  block  up  any  small  openings,  and  absolute 
tightness  is  not  required.  The  material  distributes  itself  over  a 
large  area  of  ground.  Thus  for  land  reclamation  the  value  of  this 
type  of  dredge  is  evident.  The  manner  of  working  the  dredge  and 
disposing  of  the  material  must  of  course  be  determined  by  the  local 
conditions,  and  while  the  hydraulic  type  of  dredge  has  its  limitations, 
its  sphere  of  usefulness,  as  exemplified  in  the  "King  Edward, "is 
considerably  widened. 


CHAPTER  XVI 
UNIVERSAL   DREDGES 

THE  hydraulic  dredge  was  originally  designed  to  work  exclusively 
through  very  loose  soils.  .  It  was  after  some  years  that,  in  order 
to  extend  the  field  of-  its  usefulness,  devices  were  applied  to  disinte- 
grate the  compact  soils  so  as  to  be  taken  up  by  the  pump.  The 
hydraulic  dredge  is  a  very  efficient  machine  and  superior  to  any 
other  in  working  through  very  loose  soils,  but  in  hard  and  compact 
soils  even  with  powerful  cutters  these  dredges  cannot  be  favorably 
compared  with  other  machines.  In  the  extensive  works  of  harbor 
improvement,  which,  as  a  rule,  extend  over  a  large  area,  soils  of 
different  consistency  are  encountered.  Even  if  the  cutter  suc- 
ceeded in  disintegrating  the  soils,  the  debris  composed  of  sharp 
edged  broken  stones  would  soon  disarrange-  the  pump.  Hence  in 
order  to  obtain  the  most  favorable  results  under  all  conditions,  it 
would  be  necessary  to  have  at  hand  two  different  kinds  of  dredges, 
one  for  the  loose  soils  and  another  for  working  through  hard  and 
compact  materials.  In  such  a  ycase  only  one  machine  at  a  time 
could  work,  while  the  second  would  remain  idle.  This  would  involve 
a  very  large  expenditure,  both  in  the  original  cost  of  the  larger 
plant  required  for  the  work,  and  in  its  running  expenses.  To  avoid 
this  the  two  different  classes  of  dredging  machinery  have  been 
mounted  on  the  same  hull,  resulting  in  a  new  machine,  called  the 
universal  dredge,  being  a  ladder  and  a  hydraulic  dredge  com- 
bined. Universal  dredges  are  very  powerful  machines,  built  sim- 
ilar to  regular  steamers,  able  to  navigate  in  high  seas.  They  are 
constructed  of  two  different  types,  the  universal  dredge  proper 
and  the  universal  dredge  of  the  hopper  type.  The  former  is 
the  one  which  has  on  board  the  two  sets  of  dredging  machinery, 
besides  all  the  machines  and  conveniences  for  ocean  navigation. 
The  latter  is  the  one  that,  besides  the  two  sets  of  dredging  machinery 
and  conveniences,  has  on  board  a  hopper  of  larger  capacity,  in 
which  is  deposited  the  debris  to  be  carried  away  by  the  same  steamer 

and  dumped  in  deep  waters. 

132 


UNIVERSAL  DREDGES 


133 


In  the  simple  universal  dredge  the  debris  can  be*  disposed  of  in  a 
different  manner.  For  instance  when  the  excavation  is  made  by  the 
buckets  the  materials,  after  reaching  the  upper  tumbler,  fall  into 
a  chute  and  are  dumped  into  scows  located  alongside  of  the  steamer. 
When  the  materials  are  removed  by  the  pump,  they  are  forced  to 
a  certain  height,  from  where  they  may  be  emptied  into  scows.  Or 
they  may  be  conveyed  to  shores  either  through  a  long  high  tube 
suspended  from  the  sides  of  the  vessel  as  in  the  high-tower  ladder 


FIG.  40.— Dredge  "St.  Petersburg." 

dredges;  or  may  be  conveyed  by  a  long  line  of  floating  pipes  in  the 
same  manner  as  with  the  ordinary  hydraulic  dredge. 

The  following  are  descriptions  of  these  two  types  of  the  universal 
dredge.  The  dredge  "  St.  Petersburg,"  built  by  the  Henry  Satre 
Fils  Aine  et  Cie.  for  the  Russian  Government,  is  a  universal  dredge 
proper,  while  the  "  Montevideo  I,"  built  by  Messrs  A.  F.  Smulders 
of  Rotterdam  for  the  government  of  Uruguay,  is  an  example  of  the 
universal  hopper  dredge. 

The  sea-going  dredge  "St.  Petersburg"  (see  Fig.  40),  is  provided 
with  a  ladder  with  a  bucket  chain  located  amidship  and  a  centrifugal 


134  A  TREATISE  ON  DREDGES  AND  DREDGING 

pump  for  the  hydraulic  dredging.  These  two  different  systems  of 
dredging  are  entirely  independent  of  one  another.  The  ladder 
dredge  is  used  in  the  excavation  of  soils  of  great  resistance,  while 
the  hydraulic  dredge  is  used  for  sands  or  other  finely  divided  soils. 
The  independence  of  the  two  sets  of  machinery  is  such  that  without 
dismounting  any  part,  a  change  can  be  made  instantly  from  one 
to  the  other  and  vice  versa. 

The  dimensions  of  the  dredge  are  as  follows : 

Length 131 .20  ft. 

Width 31.5    " 

Depth 10.5    " 

The  hull  is  built  entirely  of  steel  according  to  the  specifications 
of  Bureau  Veritas.  The  hull  is  open  in  front  to  allow  the  dredge 
to  cut  its  own  way  with  the  ladder  clear  out  of  water.  It  is 
divided  into  six  compartments  by  means  of  watertight  bulkheads. 
The  first  and  second  compartments  are  located  forward  and  are 
used  for  chains  and  storage.  The  third  at  the  starboard  contains 
the  quarters  for  the  crew,  the  tower  and  a  store;  the  fourth  at  the 
port  side  contains  the  messroom  for  the  officers,  and  their  sleeping 
quarters,  while  on  deck  a  large  room  provided  with  all  the  possible 
conveniences  is  reserved  for  the  engineers.  In  the  fifth  compartment 
there  are  located  all  the  boilers  and  engines  and  the  centrifugal 
pump  for  the  hydraulic  dredging. 

The  engine  is  a  compound  surface-condensing  and  reversible 
of  the  Gluck  system;  it  is  provided  with  a  friction  clutch  to  regulate 
the  speed  of  the  bucket  chain  according  to  the  resistance  of  the 
soils  encountered  in  dredging. 

When  hard  rocks  or  other  obstacles  are  encountered,  the  breaking 
of  any  part  of  the  dredging  machinery  is  avoided  by  means  of  a 
brake  acting  automatically,  thus  arresting  the  travel  of  the  bucket 
chain. 

A  starting  gear  driven  by  a  special  motor  permits  the  engines  to  be 
turned  at  slow  spee4  so  as  to  facilitate  the  mounting  or  dismounting 
of  the  bucket  chain.  In  the  same  compartment  with  the  engines 
there  is  a  well-equipped  repairing  shop. 

There  are  two  marine  boilers  of  an  improved  type.  The  fire- 
boxes are  both  extensible  and  movable.  The  heating  surface  of  the 
two  boilers  together  is  1721.6  sq.ft.  The  grates  are  of  a  special 
system  which  permit  the  use  of  any  fuel  under  the  most  favorable 


UNIVERSAL  DREDGES  135 

• 

conditions.  The  boilers  are  arranged  to  act  either  together  or 
separately  and  their  efficiency  is  such  that  one  boiler  can  provide, 
enough  power  for  both  the  dredging  and  propelling  machinery 
simultaneously. 

The  pump  for  the  hydraulic  dredging  is  lined  with  steel  through- 
out. A  special  arrangement  of  the  suction  flowing  above  the 
water  level  insures  the  floating  of  the  vessel  without  the  necessity 
of  sluices,  as  was  previously  required  in  this  type  of  dredge.  The 
articulated  joint  of  the  suction  pipe  is  located  above  the  water 
level,  so  that  it  can  be  easily  inspected  and  not  interfere  with  navi- 
gating the  vessel. 

The  engine  acting  on  the  cutter  at  the  end  of  the  suction  pipe 
is  located  to  starboard.  The  cutter  will  easily  break  up  strata  of 
hard  soils  encountered  in  dredging,  and  in  any  case  it  will  regulate 
the  proportion  of  water  and  materials  so  as  to  avoid  any  obstruction 
both  in  the  suction  pipe  and  pump. 

The  ladder  supporting  the  bucket  chain  is  very  solid  and  permits 
the  excavation  of  soils  at  different  depths  varying  from  6.5  ft.  to 
34.5  ft.  The  extreme  end  of  the  ladder  is  far  in  advance  of  the  stern 
in  order  to  dredge  its  own  way  as  stated  above,  and  also  to  dredge 
against  the  quay  walls. 

The  journals  of  the  axle  of  the  upper  tumbler  of  the  ladder  are 
provided  with  Belleville  shock  absorbers  in  order  to  eliminate 
the  shocks  produced  when  the  buckets  meet  with  some  extraordinary 
obstacle. 

The  29  buckets  of  the  ladder  are  entirely  made  of  cast  steel 
reinforced  at  their  cutting  edge  by  a  piece  of  hard  steel  easily  renewed 
when  worn  out.  The  links  of  the  chain  are  made  of  cast-steel  pieces 
and  the  bolt  holes  are  lined  with  soft  steel  so  as  to  be  easily  renewed 
when  worn  out.  The  axis  connecting  the  links  of  the  chain  with  the 
buckets  are  made  of  hard  steel. 

A  steam  crane  of  special  design  located  at  the  stern  is  used  for 
the  raising  and  lowering  of  the  ladder  and  the  lifting  of  large  blocks 
or  rocks  too  large  to  be  taken  up  by  the  buckets.  This  crane  is 
operated  by  a  reversible  engine  located  in  one  of  the  steamer  com- 
partments and  moved  by  a  belt  connection  placed  on  deck. 

All  the  various  operations  of  the  dredge  are  made  by  special 
double-cylinder  engines  easily  handled  so  as  to  have  on  board  the 
smallest  possible  crew. 

Telephones  and  electric  bells  afford  communication  between  the 


UNIVERSAL   DREDGES  137 

commanding  officers  on  deck  and  all  parts  of  the  steamer,  especially 
with  the  various  engines. 

Owing  to  the  severe  climate  in  which  this  dredge  was  to  work, 
it  was  fitted  with  all  the  conveniences,  and  the  officers'  quarters  are 
heated  both  by  steam  and  open  fire,  while  the  dredge  is  heated  by 
steam  throughout. 

On  deck  in  front  of  the  boilers  is  the  bridge,  on  which  is  located 
»  the  pilot  house. 

The  steamer  is  provided  with  two  masts  and  sails  so  as  to  navi- 
gate also  under  her  own  sails  as  it  did  from  Marseilles  to  Libau. 

The  dredge  "  Montevideo,"  see  Fig.  41,  built  by  Messrs.  A.  F. 
Smulders  of  Rotterdam,  for  the  harbor  works  of  Montevideo, 
Uruguay,  and  described  in  Engineering,  April  3;  1903,  serves  to 
illustrate  the  hopper  type  of  the  universal  dredge. 

A  special  feature  of  this  machine  consists  in  the  fact  that  it  is 
arranged  to  dredge  at  will  through  the  same  well,  either  with  a 
chain  of  buckets  or  by  means  of  a  suction  pipe.  When  using  buckets 
the  dredge  can  work  to  a  depth  of  from  13.12  ft.  to  32.81  ft.  below 
the  surface  of  the  water,  with  the  ladder  in  its  ordinary  position; 
while  by  altering  the  upper  bearing  of  this  to  a  special  support 
the  depth  reached  can  be  extended  to  42.65  ft.  below  the  water 
line.  The  minimum  efficiency  required  by  the  contract  was  an 
excavation  of  654  cu.yds.  per  hour  when  working  to  a  depth  of 
26i  ft. 

The  spoil  can  be  deliveied  from  the  dredge  either  into  a  well 
of  1046  cu.yds.  capacity,  or  into  hopper  barges  placed  alongside 
the  dredge.  The  distance  of  the  top  of  the  wells  of  these  barges 
when  light  is  9.84  ft.  above  the  water  level,  and  6.56  ft.  away 
from  the  dredge  horizontally.  When  carrying  its  own  spoil  the 
dredge  was  required  not  to  draw  more  then  13.94  ft.  and  to  be  capable 
of  steaming  out  to  sea  with  its  own  screw  for  unloading.  When 
arranged  for  suction  dredging  the  machine  is  designed  to  work  at 
depths  of  from  13.12  ft.  up  to  32.81,  and  when  working  at  depths  of 
26J  ft.  it  was  required  to  fill  its  wells  of  1046  cu.yds.  capacity  in 
40  minutes.  With  wells  laden  its  speed  on  proceeding  to  sea  was 
required  to  be  not  less  than  7  knots,  and  its  engines  were  also  required 
not  to  consume  more  than  2.20  Ibs.  of  coal  per  indicated  horse- 
power per  hour.  The  dredge  when  finished  proceeded  to  Monte- 
video under  its  own  steam. 

The  hull  is  of  Siemens-Martin  steel,  and  is  241  ft.  long  by  41  ft. 


138  A  TREATISE   ON  DREDGES  AND   DREDGING 

wide  by  17  ft.  3  in.  depth  of  hold.  The  hopper  has  a  capacity  of 
1250  tons  and  fc  50  ft.  long  by  33  ft.  10  in.  wide  at  the  top  and  23  ft. 
wide  below.  Fully  laden,  and  carrying  50  tons  of  coal  in  the  bunkers 
and  5  tons  of  water  in  the  boilers,  the  draft  is  13.94  ft.  The 
mean  speed  attained  on  runs  with  and  against  the  current  was 
8.2  knots.  Installed  in  the  hull  are  two  compound  engines  placed 
nearly  amidship,  which  drives  at  will  either  the  bucket  chain,  the 
centrifugal  pumps  for  the  suction  apparatus,  or  the  two  propelling 
screws.  The  two  engines  together  develop  1000  indicated  horse- 
power. They  are  supplied  with  steam  by  two  ordinary  return-tube 
boilers,  placed  forward  and  built  of  steel  under  the  Veritas  rules  for 
a  working  pressure  of  113.8  Ibs.  per  sq.in.  The  two  together  provide 
a  heating  surface  of  3444  sq.ft.  The  steam  for  the  dynamo  engine 
and  for  the  centrifugal  circulating  pump  is  also  taken  from  these 
boilers,  which  are  fed  by  two  Worthington  pumps.  There  are  also 
eight  steam  winches  which  are  used  in  maneuvering  the  craft. 
The  framing  carrying  the  upper  pinion  for  the  dredging  chain  is 
removable  above  the  deck  level.  The  forward  legs  are  secured 
to  the  sides  of  the  well,  while  the  rear  legs  rest  on  deck,  which  is 
stiffened  below  by  a  strong  beam  running  across  the  hull.  The  total 
distance  from  the  bottom  of  the  hull  to  the  top  of  the  pinion  framing 
is  53.31  ft. 

The  ladder  frame  is  a  built  beam  88.58  ft.  long  and  allows  dredging 
to  be  done  in  depths  of  13.12  ft.  to  32.81  ft.  of  water  without  shifting 
the  upper  support  of  the  ladder.  The  upper  pinion  is  of  square 
section,  and  was  cast  in  a  single  piece  out  of  white  iron.  The  lower 
pinion  is  hexagonal,  and  is  a  steel  casting.  The  buckets,  of  which 
there  are  32,  have  a  capacity  of  28  cu.ft.  and  have  the  back  sides 
and  lips  of  cast  steel,  while  the  body  is  of  steel  plate.  The  links 
are  alternately  steel  castings  of  double  T  sections  and  steel  plates. 
They  are  provided  with  renewable  bushing  of  manganese  steel, 
which  can  be  readily  replaced  after  wear.  The  bolts  are  also  of 
manganese  steel,  and  have  square  heads.  The  bucket  speed  is 
such  as  to  bring  16  over  the  top  pinion  every  minute. 

The  transmission  gear  fitted  to  the  main  engines  allows  either 
of  them  to  be  used  for  driving  the  chain,  or  each  for  running  a 
centrifugal  suction  pump.  It  is  also  possible  to  use  one  engine  for 
driving  both  screws,  while  the  other  runs  one  of  the  centrifugal 
pumps.  In  the  latter  case  one  of  the  screws  is  driven  by  means  of 
gearing.  The  centrifugals  are  driven  from  the  engine,  but  the  dredg- 


UNIVERSAL  DREDGES  139 

ing  chain  is  driven  through  steel  spur  and  bevel-gearing  by  means 
of  friction  clutches,  which  slip  in  the  case  of  an  excessive  load  on  the 
chain,  and  thus  prevent  breakage.  The  centrifugal  pumps  are 
driven  direct  through  claw  couplings  on  the  crank-shafting,  and 
are  designed  for  a  maximum  speed  of  150  revolutions  per  minute. 
They  are  built  up  of  steel  plates  and  angles,  renewable  plates  of 
steel  being  fitted  inside  the  casings.  The  latter  are  designed  so  as  to 
admit  of  the  interior  of  the  pump  being  easily  inspected.  The  impel- 
lers have  four  arms,  also  fitted  with  renewable  wearing  plates.  The 
suction  is  long  enough  to  allow  of  dredging  to  a  depth  of  32.8  ft. 
It  is  so  fashioned  that  with  the  dredge  steaming  fully  laden  it  can 
be  carried  entirely  above  the  water  level.  The  discharge  pipe  from 
the  pumps  is  of  rectangular  section,  and  runs  along  almost  the 
whole  length  of  the  hopper.  It  is  provided  with  sluice  openings 
corresponding  to  each  section  of  the  hopper. 

Six  cabins  are  provided:  one  each  for  the  engineer,  the  chief 
dredgeman,  the  chief  mechanical  engineer,  and  two  others  for  the 
two  assistants  of  each,  while  the  sixth  is  reserved  as  messroom. 
The  accommodation  for  the  crew  is  sufficient  for  the  needs  of  ten  men. 

The  boat  is  lighted  electrically  by  means  of  three  1000-candle- 
power  arc  lamps,  in  addition  to  incandescent  lamps  in  the  cabins  and 
engine  rooms  and  stokehold. 

The  navigating  bridge  is  placed  in  front  of  the  funnel,  and  is  fitted 
with  steam  steering-gear  engine,  telegraphs,  and  the  like.  A  single 
foremast  is  fitted  as  shown  in  the  figure. 

The  results  obtained  on  the  official  trials,  made  on  behalf  of  the 
Uruguayan  Government  on  the  Meuse,  during  a  period  of  fifteen 
days,  are  given  below: 

Condition  of  Content.  Actual  Results. 

Dredging  by  bucket,  output  per  hour 500  cu.m.  650  cu.m. 

Suction  dredging,  output  per  hour 1200  cu.m.  1800  cu.m. 

Speed 7  knots  8.2  knots 

Fuel  consumption,  per  I.H.P.  per  hour 1  kg.  0.95  kg. 


CHAPTER  XVII 
STIRRING   DREDGES 

STIRRING  dredges  can  be  sometimes  employed  with  advantage 
for  the  removal  of  materials  from  the  bottom  of  rivers  and  harbors. 
When  the  bottom  is  composed  of  very  finely  divided  particles  it  is 
evident  that  by  stirring  up  these  deposits  while  the  water  has  a  given 
velocity,  the  water  will  carry  in  suspension  the  particles  to  be  depos- 
ited again  at  a  great  distance  from  the  original  point.  Then  the 
dredging  operation  is  simply  reduced  to  stirring  up  the  materials  at 
the  bottom,  while  the  water  acts  as  a  means  of  transportation, 
and  the  erosive  dredges  used  for  such  a  purpose  will  be  simply 
provided  with  a  device  for  the  agitation  of  the  materials. 

For  the  successful  employment  of  the  stirring-up  process  as  a 
means  of  excavating  the  bottom  of  channels,  rivers,  harbors,  etc., 
two  conditions  should  be  satisfied:  First,  the  material  should  be 
reduced  to  very  finely  divided  particles  so  as  almost  to  float  when 
agitated,  and  consequently  it  is  only  applicable  to  the  finest  sands 
and  muds.  Second,  the  water  holding  these  materials  in  suspension 
should  have  such  velocity  of  flow  as  to  carry  them  to  deep  water 
or  to  localities  where  they  will  not  interfere  with  navigation  before 
depositing  them.  Hence  this  method  of  dredging  can  only  be 
applied  under  given  conditions.  Thus  in  the  harbors  and  tidal 
rivers  it  cannot  be  used,  but  during  the  ebb  tide  and  in  the 
ordinary  rivers  where  the  velocity  of  water  is  such  that  will  permit 
the  materials  to  remain  in  suspension  until  deep  waters  will  have 
been  reached,  thus  preventing  the  formation  of  other  obstructions 
down  stream. 

Different  devices  have  been  used  to  agitate  the  bottom ;  the  most 
common  being  the  harrow,  the  revolving  drums,  the  screw  propeller 
and  the  pump.  All  those  that  have  been  used  and  have  given 
good  results  will  be  described.  There  are,  however,  numerous  other 
methods  all  covered  by  letters  patent.  A  long  list  of  these  devices 
can  be  found  in  the  paper  on  Dredges  and  Dredging  in  the  Mississippi 

140 


STIRRING  DREDGES  141 

River,  by  Mr.  J.  A.  Ockerson,  C.  E.,  Trans.  Am.  Soc.  G.  E.,  Vol.  XL. 
This  long  list  of  patents  is  due,  so  Mr.  Ockerson  saye,  to  the  fact  that 
the  United  States  Government  offered  a  premium  of  $100,000  for 
the  best  means  of  removing  the  sand-bars  alongt  he  Mississippi 
River.  No  wonder  that  the  attention  of  so  many  inventors  was 
turned  in  this  direction. 

Harrows  and  Scrapers.  Since  the  Middle  of  the  14th  century 
the  Venetians  have  employed  the  stirring  process  for  the  removal 
of  sand-bars  which  were  formed  by  the  accumulated  deposits  of 
the  tide,  and  they  made  use  of  the  ebb  tide  as  a  vehicle  to  transport 
the  materials  away  from  the  point  of  excavation.  At  that  time 
the  stirring  was  done  by  scraping  the  bottom  with  iron  harrows 
attached  to  long  wooden  handles.  They  were  operated  by  men  in 
small  boats.  The  operation  was  carried  on  during  the  ebb  tide 
only,  so  that  the  suspended  materials  were  carried  out  to  sea  by 
the  receding  water. 

The  method  was  used  in  England  years  ago.  Mr.  Cresy,  in 
his  Encyclopedia  of  Civil  Engineering,  thus  describes  the  Floating 
Clough,  a  machine  used  for  scouring  out  the  channel  of  the  river 
at  Great  Grimsby  and  also  on  the  Humber.  The  scraper  used  was  a 
frame  12  ft.  long,  9  ft.  wide  and  6  ft.  deep  of  6  x  4-in.  timber,  covered 
with  2-in.  plank,  through  the  middle  of  which  was  a  culvert  2  ft. 
6  in.  wide,  made  of  planks,  with  a  small  lifting  door  at  one  end. 
At  the  bottom  two  beams  projected  in  front,  serving  as  feelers  to 
keep  the  machine  in  its  right  position.  In  front  are  placed  frames 
of  timber  shod  with  iron,  cut  in  a  serrated  form,  which,  by  means 
of  a  lever,  can  be  raised  at  pleasure.  At  the  sides  of  the  machine 
are  wings,  sloped  to  accommodate  themselves  to  the  fall  of  the  banks. 
The  machine  is  moored  in  the  middle  of  the  stream,  with  the  wings 
extended  by  means  of  ropes,  and  at  half  flood  the  water  is  admitted 
into  the  scraper  by  removing  the  plugs,  and  the  machine  sinks  to 
the  bottom ;  the  plugs  are  then  replaced,  and  the  scraper  remains  in 
this  position  till  flood  tide.  The  iron-shod  frame,  with  teeth  like  a 
saw,  are  let  down  in  front,  and  the  whole  machine,  being  forced 
along  by  the  tide,  scrapes  up  the  bottom,  and  the  mud  disturbed  is 
carried  along  by  the  receding  tide  for  a  distance  of  three  miles  or 
more  in  the  space  of  two  hours. 

In  the  United  States  the  method  of  dredging  by  stirring  up 
the  materials  was  successfully  employed  in  the  improvement  of 
the  mouth  of  the  Mississippi  River.  In  the  years  1853-1858 


142  A  TREATISE   ON  DREDGES  AND   DREDGING 

and  1860  the  channels  were  cleared  by  raking  or  harrowing  the 
bottom,  and  they  remained  cleared  as  long  as  operations  were 
continued,  while  as  early  as  the  years  1837  and  1839  the  use  of 
dipper  dredges  served  by  scows  proved  a  failure,  since  in  a  one  night 
storm  all  the  materials  that  had  been  removed  after  a  great  expen- 
diture of  time  and  money  were  brought  back.  For  this  reason 
Major  M.  D.  McAlester,  U.  S.  A.  Corps  of  Engineers,  in  the  report 
of  the  Chief  of  Engineers  for  the  year  1866,  states  that  the  plan  of 
stirring  up  the  sediment  forming  the  bars  within  the  limits  where 
greater  depth  of  channels  is  required  is  most  efficacious  and  eco- 
nomical. 

In  the  harrowing  process,  successfully  applied  in  the  50's  the 
machine  consisted  essentially  of  a  wooden  frame  of  rectangular 
shape,  one  end  of  which  wras  attached  horizontally  to  the  stern  of 
a  sidewheel  steamer  and  turned  about  a  horizontal  axis,  while  the 
other  contained  the  iron  teeth  for  harrowing  and  was  held  in  contact 
with  the  bottom  of  the  channel,  and  raised  entirely  out  of  order, 
as  necessity  called  for,  by  means  of  tackling  rigged  to  shears  resting 
on  the  deck  of  the  vessel.  In  using  this  machine  many  interruptions 
of  work  occurred,  owing  to  the  necessity  of  repairing  the  parts  of 
the  rake  damaged  in  consequence  of  impact  with  wrecks. 

On  the  same  principle  more  powerful  machines  were  constructed 
later  on  and  used  in  different  sections  of  the  Mississippi  River. 
Thus,  for  instance,  in  the  year  1867  an  appropriation  of  $96,000  was 
made  for  the  construction  of  two  dredges,  the  " Montana"  and  the 
"  Caffrey  "  to  be  used  on  the  upper  Mississippi  River  between  St.  Paul 
and  the  mouth  of  the  Illinois  River.  The  dredges  were  sidewheel 
steamers.  The  "  Montana  "  was  210  ft.  long,  35  ft.  beam  and  oj  depth 
of  hold,  and  was  equipped  with  two  engines  having  20-in.  cylinders 
and  7-ft.  stroke;  while  the  "Caffrey"  was  150  ft.  long,  30  ft.  wide, with 
4J-ft.  hold,  with  a  draft  of  32  in.  She  had  15-in.  cylinders  with 
5-ft.  stroke.  These  dredges  were  equipped  with  scrapers  designed 
by  Col.  Long.  These  scrapers  consisted  of  a  frame  attached  to  the 
bow  of  the  boat  and  carrying  a  heavy  crossbar  to  which  were  attached 
six  steel  buckets  or  cutters.  This  frame  could  be  raised  or  lowered 
at  will.  In  operating,  the  boat  went  to  the  upper  side  of  a  reef,  the 
scraper  was  lowered  and  the  boat  was  then  backed  slowly  down- 
stream, scraping  the  sand  with  it  down  to  deep  water  below  the  reef. 
This  operation  was  repeated  until  the  desired  depth  was  obtained. 

This  scraping  was  continued  for  several  years  at  a  cost  of  about 


STIRRING  DREDGES  143 

$20,000  per  each  steamer,  but  since  the  relief  was  only  temporary 
and  had  to  be  repeated  from  year  to  year,  it  finally  gave  place  to 
the  so-called  permanent  improvement,  consisting  mainly  of  channel 
contraction. 

Stirring  by  Revolving  Wheels.  The  agitation  of  the  bottom  by 
means  of  revolving  wheels  has  been  done  in  two  different  ways,  viz., 
by  the  Bishop  conical  screws  and  by  propellers. 

The  Bishop  conical  screws  consist  of  two  conical  screws  abutting 
together  at  their  vertices  and  spreading  out  at  their  bases  so  as  to 
form  a  flat  letter  V.  These  are  supported  by  a  heavy  upright  frame 
to  be  attached  to  the  bow  of  a  vessel  and  arranged  to  raised  or 
lowered  so  as  to  bring  the  screws  in  contact  with  the  bar,  the  point 
of  the  V  being  forward.  The  screws  are  revolved  on  bearings  at 
the  two  ends  of  each  by  guard  wheels,  run  by  the  engines  of  the 
vessel  to  which  the  machine  is  attached,  or  by  an  auxiliary  engine 
if  desired.  They  are  connected  with  the  motor  by  endless  chains. 
The  screws,  revolving  in  opposite  directions,  were  expected  to  cut 
a  furrow  through  the  bar,  breaking  up  its  surface  and  washing  it  up 
into  the  river  current  to  be  floated  away.  This  device  was  applied 
to  the  steamer  "Wiggins  "  in  1867,  but  gave  unsatisfactory  results 
owing  to  the  fact  that  the  screws,  lowered  to  16  or  18  ft.  into  the 
water  and  projecting  far  from  the  front  of  the  vessel,  made  the 
machine  clumsy,  so  it  became  unmanageable  in  the  muddy  water. 

The  steamer  "  Wiggins,"  on  which  the  Bishop  screws  were  tried, 
was  provided  with  two  conical  screws  20  ft.  long,  5  ft.  in  diameter 
at  their  bases,  and  placed  in  such  a  manner  that  their  points  came 
together  in  front  of  the  boat's  cutwater,  and  their  bases  were  sep- 
arated from  each  other  so  as  to  measure  about  20  ft.  from  "out  to 
out. "  They  were  mounted  so  that  their  axes  were  horizontal. 
Their  flanges  were  12  ft.  wide  at  the  base  of  the  cones,  diminishing 
to  6  in.  at  the  points. 

Propellers.  Propellers  of  large  diameter  were  also  used  to  stir  up 
the  materials  from  the  bottom  of  channels.  In  the  year  1859  Mr. 
Charles  Hyde,  noticing  the  small  progress  made  by  the  scrapers  in 
removing  sand-bars,  decided  to  adopt  more  powerful  means  of 
agitating  the  materials  and  used  the  propeller  "  Enoch  Train."  A 
vessel  was  constructed  with  two  ship's  propellers  at  the  stern  and 
with  water  tanks  which  could  be  filled  to  sink  the  hull  so  as  to  bring 
the  propellers  in  contact  with  the  bar  and  by  their  revolution  cut 
and  stir  it  up,  to  be  swept  away  by  the  river  current. 


144  A  TREATISE   ON  DREDGES  AND   DREDGING 

In  the  year  1867  Major  McAlester  designed  the  U.  S.  dredge 
"Essayon"  using  the  propeller  "  Enoch  Train  "  as  a  means  of  stirring 
up  the  material.  The  dredge  boat  "Essayon"  was  a  double-ender 
provided  with  two  strong  and  powerfully  driven-screw  propellers, 
one  at  each  end,  driven  by  separate  engines.  She  was  provided  with 
watertight  compartments  so  that  when  empty  the  vessel  drew 
16  ft.  and  when  full  of  water  24  ft.  The  total  depth  of  the  vessel 
from  the  spar  deck  to  the  bottom  of  the  keel  was  26  ft.  Her  spar 
deck  was  nearly  flat  and  clear  of  obstruction  from  both  ends  to 
near  amidship,  to  facilitate  the  addition  at  any  time  of  any  other 
device  which  would  be  found  necessary.  It  was  provided  with  a 
single  pilot  house  located  amidship.  The  screw  propellers  were 
16  ft.  in  diameter,  describing  circles  equal  to  the  minimum  draft 
of  the  vessel.  The  propellers  were  provided  with  four  blades  and 
their  ends  were  shaped  so  as  to  readily  cut  away  compact  mud.  The 
dredge  "  Essay  on  "  was  built  by  the  Atlantic  Works,  Boston,  Mass., 
at  a  cost  of  $223,000.  It  was  found  very  efficient.  The  depth  of 
water  on  the  bar  at  Pass  a  T Outre  was  increased  from  11  ft.  6  in. 
to  17  ft.  8  in.  and  kept  at  such  a  depth.  But  long  delays  to  the 
work  were  caused  by  repairing  the  blades  of  propellers,  which  were 
easily  and  frequently  broken  by  obstructions  encountered.  This 
fact  suggested  some  modifications,  which  were  introduced  on  a 
second  dredge  of  the  same  type,  called  "McAlester,"  in  which  the 
propellers  were  more  solidly  built.  A  plow  was  placed  in  front 
of  the  excavating  screws  and  also  a  large  scraper,  18  ft.  across  and 
10  ft.  high,  to  be  lowrered  directly  in  front  of  the  plow,  to  make 
the  machine  more  efficient  ahd  prevent  the  breaking  of  the  blades 
of  the  propeller  by  coming  in  contact  with  obstructions. 

Stirring  by  Jets.  To  stir  up  sand-bars  by  forcing  a  jet  of  water 
upon  them  was  suggested  by  Messrs.  Scott  and  McClintock.  They 
constructed  a  machine  for  forcing  jets  of  water  at  high  pressure  so  as 
to  dislodge  the  sand  and  mud.  Although  this  method  did  not  work 
well  at  the  delta  of  the  Mississippi  River,  where  the  material  varied 
from  sand  and  mud  to  gravel  and  clay,  yet  it  was  successful  in  other 
cases  where  the  bars  were  formed  by  very  fine  sands.  In  the  Report 
of  the  Chief  of  Engineers  for  the  year  1882  is  given  a  description  of 
a  hydraulic  excavator  which  was  used  in  the  improvement  of  the 
Mississippi  River  and  employed  in  grading  the  banks  for  receiving 
a  revetment.  The  excavator  consisted  simply  of  a  powerful  steam 
pump  placed  upon  a  scow  and  furnished  with  the  necessary  boiler 


STIRRING  DREDGES  145 

power  and  hose  for  throwing  powerful  jets  of  water.  The  boiler 
was  20  ft.  long  and  42  in.  in  diameter  with  two  14-in.  flues  and  had  a 
nominal  25  H.P.  The  pump  provided  two  jets  thrown  from  2-in. 
nozzles,  the  water  being  conducted  from  the  pumps  to  the  desired 
point  through  flexible  4J-in.  6-ply  hose.  By  a  special  arrangement 
the  steam  was  guided  by  only  one  man.  Although  in  this  case  the 
excavator  was  used  more  properly  for  land  work  than  for  dredging, 
yet  the  same  device  was  applied  one  year  later  to  stir  up  the  material 
at  the  bottom  so  as  to  easily  enter  the  lower  end  of  a  suction  tube 
of  a  hydraulic  dredge. 

For  many  years  the  harbor  of  Swansea ,  whose  bottom  was  com- 
posed of  fine  sand  and  mud,  was  kept  clean  by  means  of  the  stirring 
process.  The  machine  employed  was  a  powerful  steam  pump 
mounted  on  a  boat.  At  the  beginning  of  the  ebb  tide  the  pump 
was  put  in  motion  and  the  boat  sailed  along  determined  courses, 
agitating  the  bottom,  and  the  fine  particles  of  the  materials  that 
were  very  light  floated  in  the  water  and  were  carried  away  by  the 
receding  tide.  The  machine  could  work  only  a  few  hours  a  day 
and  by  changing  continuously  the  course  of  the  boat,  the  harbor 
was  scoured  in  all  directions  and  the  bottom  kept  at  a  given  level. 
This  method  has  now  been  abandoned  and  a  powerful  double  ladder 
dredge  has  been  substituted,  not  only  for  cleaning  the  harbor,  but 
to  deepen  its  bottom  so  as  to  accommodate  vessels  of  larger  capacity. 

Revolving  Drums.  Revolving  drums  or  rolters  have  been  used 
to  stir  up  the  material  and  thus  allow  it  to  be  carried  away  by  the 
velocity  of  water.  One  of  these  machines,  called  the  "  hedgehog/' 
was  used  in  Lincolnshire  and  is  thus  described  by  Mr.  Ed.  Cresy  in 
his  Encyclopedia  of  Civil  Engineering. 

The  "  hedgehog  "  in  use  for  removing  mud  in  rivers,  or  the  accu- 
mulation on  the  land  side  of  sea-sluices;  is  cylindrical  in  its  form, 
like  a  garden  roller.  Around  the  outside  are  attached  eight  or  more 
longitudinal  ribs,  each  of  which  is  armed  with  as  many  spades 
or  hoes  fixed  in  them  firmly  by  bolts  and  screws.  This  cylinder 
revolves  on  pivots  in  gudgeons  in  the  side  frame,  which  is  made  of 
oak,  and  diagonally  braced  in  front  of  the  roller  or  the  revolving 
cylinder.  The  iron  spades,  9  in.  long  and  4  in.  wide,  placed  about  7  in. 
apart  at  each  end  of  the  shaft,  are  attached  to  a  strong  chain,  by 
which  it  is  moved.  When  used  it  is  attached  to  the  stern  of  a  barge, 
which  in  Lincolnshire  is  usually  drawn  by  horses.  Sometimes  a 
barge  is  moored  at  some  distance  from  the  mouth  of  the  sluice  to 


146  A  TREATISE  ON  DREDGES  AND   DREDGING 

be  cleansed,  and  the  "hedgehog"  is  moved  backward  and  forward 
by  blocks  and  chains.  Such  a  machine,  made  of  oak  and  well  bolted 
together,  is  most  effective;  as  the  cylinder  revolves  on  its  axis, 
its  sixty-four  spades  are  all  brought  into  work,  thus  stirring  up  a  vast 
quantity  of  mud,  which  the  stream  through  the  sluice  aids  in  carry- 
ing away.  The  timber  frame  is  scantling  6  in.  by  4  in.,  cross-stays 
from  one  side  to  the  other  being  placed  3  ft.  apart;  and  between 
them  are  diagonal  braces,  which  are  made  fast  to  the  frame  and 
stays  by  iron  bolts.  The  stocks  on  the  cylindrical  drum  or  iron 
wheel  are  6  ft.  long  and  made  of  oak  6  by  4  in.;  into  which  pass  the 
iron  spades. 


CHAPTER  XVIII 
PNEUMATIC  DREDGES 

COMPKESSED  air  has  been  used  for  dredging  purposes.  Although 
in  the  form  used  it  proved  to  be  more  expensive  than  any  other 
process,  yet  there  are  cases  in  which  it  might  be  found  economical. 
For  this  reason  the  writer  has  collected  all  the  information  possible 
on  this  subject,  having  obtained  it  from  the  Scientific  American, 
Engineering  News  and  Compressed  Air  Magazine. 

Pneumatic  dredging  was  done  at  Uleaborg,  Finland,  with  a 
dredge  designed  by  M.  Jandin  of  Lyons,  France.  This  dredge 
was  used  to  excavate  a  canal  20  ft.  deep  from  the  city  of  Uleaborg 


FIG.  42. — Jandin  Method  for  Sinking  Tubular  Piers. 

to  the  Gulf  of  Bothnia  at  the  mouth  of  the  River  Ulea,  where  the 
depth  of  water  had  been  reduced  to  about  13  ft.  by  accumulations 
of  sand. 

M.  Jandin  applied  in  this  dredge  an  apparatus  which  he  had 
successfully  employed  in  sinking  tubular  piers  for  the  Palma  del 
Rio  bridge  over  the  Guadalquivir  River.  The  apparatus  (see  Fig. 
42)  consisted  of  a  tube  8  in.  in  diameter  and  connected  at  the  bottom 

147 


148  A  TREATISE   ON  DREDGES   AND   DREDGING 

with  another  smaller  tube  carrying  compressed  air,  which  passed 
into  the  discharge  columns  by  an  annular  orifice.  The  principle 
upon  which  the  device  works  is  that  a  mixture  of  air  and  water 
is  formed  in  the  discharge  column,  which  is  lighter  than  the  water 
outside,  and  the  difference  in  pressure  is  sufficient  to  create  such  a 
velocity  that  the  discharging  current  will  carry  with  it  a  certain 
amount  of  the  material  to  be  excavated. 

The  apparatus  can  be  used  to  depths  of  131  to  164  ft.  below 
the  water  surface,  in  suitable  material,  without  exceeding  an  air 
pressure  of  2  atmospheres.  The  only  conditions  for  its  successful 
use  are  a  depth  of  water  of  at  least  10  ft.  and  a  height  of  discharge 
having  for  its  practical  limit  one-third  of  the  depth.  The  same 
system  can  be  successfully  used  to  transport  materials  horizontally, 
the  friction  in  the  conduit  being  much  decreased  by  the  air  mixed 
with  water. 

In  the  dredge  designed  for  the  Canal  at  Uleaborg  the  excavating 
apparatus  consisted  of  a  hydro-pneumatic  dredging  pipe,  which 
raised  the  mixture  of  water  and  excavated  material,  and  emptied 
it  into  a  large  cylindrical  reservoir,  which  constituted  the  forcing 
apparatus.  The  dredging  pipe,  the  orifice  of  which  rested  constantly 
upon  the  bottom,  formed  the  axis  of  a  rigid  frame  which  was  guided 
vertically  by  the  sides  of  a  well  at  the  extremity  of  the  boat.  Its 
upper  part  was  connected  with  a  horizontal  pipe  which  entered 
the  reservoir  through  a  flexible  elbow.  Near  the  lower  orifice  of 
the  dredging  pipe  there  was  arranged  an  annular  injector,  which 
introduced  compressed  air  into  the  pipe.  This  injection  of  air 
produced  a  suction,  while  at  the  same  time  it  formed  in  the  pipe 
a  mixture  of  air,  water  and  material  carried  along  by  the  water, 
a  mixture  whose  density  was  less  than  that  of  the  Water.  It  is 
easily  conceived  that  with  a  given  depth  of  water  it  was  possible, 
with  the  coefficients  furnished  by  experiments,  to  calculate  the 
volume  of  air  necessary  to  make  the  external  charge  upon  the  orifice 
greater  than  the  weight  of  the  column  of  the  mixture  ascending 
above  the  level  of  the  water  to  a  fixed  height. 

The  principal  advantage  of  this  system  is  that  there  is  no  obstruc- 
tion possible,  as  the  orifice  presents  a  passage  that  is  smaller  than 
the  constant  section  of  the  pipe,  and  no  parts  in  motion  are  in  contact 
with  the  excavated  material.  In  this  way  are  avoided  two  of  the 
inconveniences  of  pumps  applied  to  dredging,  and  which  cause 
frequent  stoppages  and  necessitate  costly  repairs. 


PNEUMATIC  DREDGES  149 

9 

Jets  of  compressed  air,  arranged  around  the  orifice  and  directed 
against  the  earth,  disintegrate  the  latter  and  increase  the  proportion 
of  the  material  carried  along  by  the  velocity  of  the  water;  a  pro- 
portion which  in  ordinary  depths  of  20  or  25  ft.  reaches,  as  regards 
sand,  25  per  cent  of  the  volume  of  water. 

The  suction  pipe  10  in.  in  diameter  was  actuated  by  a  compressor 
of  the  capacity  of  211  cu.ft.  of  free  air  per  minute.  The  forcing 
apparatus  consisted  of  a  cylindrical  reservoir  10  ft.  in  diameter  and 
22  ft.  long  with  convex  ends  having  a  capacity  of  176  cu.ft.  This 
received  the  mixture  of  water  and  material,  the  air  escaped  through 
an  opening  surmounted  by  an  open  dome,  upon  the  side  of  which 
there  was  a  wastepipe.  When  the  reservoir  was  full  and  the  water 
was  making  its  escape  through  the  wastepipe,  a  single  external 
lever,  operated  by  the  chief  dredgeman,  closed  valves  that  in  turn 
closed  internally  the  orifice  of  the  dredging  pipe,  and  opened  the 
air  port,  and  at  the  same  time  reversed,  through  three-way  cocks, 
a  current  of  compressed  air,  which  was  then  forced  through  distinct 
pipes  into  the  reservoir  and  led  to  injection  tubes,  properly  spaced 
in  the  lower  part  of  the  reservoir.  The  effect  of  the  jets  of  compressed 
air,  formed  under  the  mass  of  earth  and  water,  was  to  lift  the  material 
while  mixing  it  with  water  and  throwing  it,  as  if  by  successive  shovel- 
fuls, toward  the  orifice  situated  at  the  lowest  point  of  the  excavation. 

The  air  traversed  the  mass  of  water  and  material  and  flowed  to 
the  upper  part  of  the  reservoir,  where  was  gauged  the  pressure,  cor- 
responding to  the  distance  and  height  to  which  the  material  was 
forced. 

The  total  time  taken  to  force  to  a  distance  of  1000  ft.  was  six 
minutes,  two  of  which  were  consumed  in  the  passage  through  the 
conduit.  The  tubing  or  pipe  was  filled  by  the  escape,  at  the  end  of 
the  conduit,  of  a  wheat-sheaf  jet  of  water  and  air  projected  through 
an  explosion  to  48  ft.  from  the  orifice,  the  conduit  remaining  empty 
and  being  cleaned  out  by  this  final  action  of  the  air.  At  the  same 
time  the  automatic  valve  that  closed  the  upper  orifice  of  the  reservoir 
was  opened  by  its  own  weight.  The  lever  that  worked  the  cock  was 
then  reversed  and  the  air  sent  to  the  dredging  pipe  and  the  pipe  was 
again  filled. 

Thus  the  dredging  and  forcing  occurred  successively  at  periods 
of  from  5  to  6  minutes,  the  boat  remaining  immovable  during  the 
forcing  period. 

The    compressor   used    was    provided    with    double   horizontal 


150  A  TREATISE  ON  DREDGES  AND  DREDGING 

cylinders  and  was  driven  directly  by  two  compound  steam  cylinders 
with  variable  expansion,  with  condenser.  The  advantage  of  this 
arrangement  was  that,  since  the  expansion  was  effected  success- 
ively in  the  two  steam  cylinders,  the  stress  upon  the  piston  varied 
within  quite  narrow  limits.  This  suited  the  conditions  of  the  work 
of  compression,  as  the  maximum  stress  was  produced  in  the  com- 
pressing cylinders  during  the  period  of  forcing  the  excavated  material. 

The  carrier  or  conveyor  consisted  of  two  iron  plate  pipes  with 
Jandin's  joints  of  steel  rings  and  rubber  washers,  secured  with 
conical  pins.  Here  and  there  were  arranged  flexible  joints,  which 
were  likewise  employed  for  the  jointing  of  the  dredge  pipe  and  the 
connecting  of  the  floating  conveyor  with  the  forcing  apparatus 
carried  by  the  boat. 

The  dredge  was  self  propelling.  The  boat  was  maneuvered  by 
means  of  mooring  chains  anchored  at  a  great  distance  and  payed 
in  and  out  by  four  steam  winches  located  one  at  each  corner  of  the 
deck  of  the  pontoon  upon  which  were  mounted  all  the  machinery. 

Pneumatic  dredging  is  specially  adapted  to  the  forcing  of  the 
dredged  material  to  a  great  distance,  or  to  elevating  it  upon  the 
bank  to  considerable  heights,  for  the  pressure  at  the  beginning  of 
the  conduit  may  easily  reach  three  atmospheres,  which  would 
effect  an  elevation  to  95  ft. — a  height  that  exceeds  the  ordinary 
conditions.  When  the  material  is  to  be  forced  but  a  short 
distance,  as  emptying  it  behind  a  jetty,  the  system  may  be  so  arranged 
that  the  dredging  and  forcing  may  be  effected  continuously  and 
simultaneously.  The  dredging  pipe  is  then  prolonged  directly  to 
the  floating  conveyor,  to  which  it  is  attached  by  a  flexible  metallic 
elbow. 

In  hydraulic  mining  a  hydraulic  elevator  is  sometimes  used 
to  raise  the  sluiced  material  from  the  bottom  of  pits  and  river 
bottoms.  The  sluiced  material  entering  the  pipe  is  met  by  a  jet 
of  water  under  pressure  which  forces  the  material  to  the  desired 
height.  The  efficiency  of  the  elevator  is  increased  by  an  auxiliary 
opening  admitting  the  proper  proportion  of  air.  Material  is  raised 
in  this  manner  100  ft.  or  more.  This  might  be  termed  a  form  of 
dredging. 


CHAPTER  XIX 
DIPPER  DREDGES— GENERAL  DISCUSSION 

.  THE  dipper  dredge  can  be  likened  to  an  ordinary  steam  shovel 
mounted  on  a  scow  or  float.  This  machine  is  very  convenient  for 
dredging  in  shallow  waters  and  has  been  extensively  used  along 
the  shores  of  the  Great  Lakes  and  in  the  excavation  of  canals  for 
drainage  purposes  on  the  flat  and  marshy  lands  along  the  rivers  and 
seashores  of  the  Atlantic  and  Gulf  coasts.  It  has  done  extensive 
and  important  work  at  a  comparatively  low  cost,  so  that  to-day 
many  contractors  and  engineers  believe  implicitly  in  the  efficiency 
of  the  dipper  dredge,  and  prefer  this  machine  to  any  other  type  of 
dredge. 

The  hull  is  built  with  a  flat  bottom,  so  as  to  allow  the  machine 
to  float  even  in  very  shallow  water.  The  hull  is  always  made  of 
wood,  formed  with  keelsons  and  floor  planking  caulked  in  the  usual 
way.  The  deck  is  formed  by  beams  connected  to  the  keelson  by 
means  of  verticals,  supporting  a  heavy  caulked  planking.  The  bow 
and  stern  sides  of  the  hull  are  formed  in  the  same  way  by  beams 
planked  and  caulked.  In  dredges  of  large  capacity,  in  order  to 
support  the  heavy  boom  and  its  attachment  and  at  the  same  time 
to  stiffen  the  structure  so  as  to  prevent  any  damage,  the  hull  is 
reinforced  by  steel  trusses.  Two  trusses  are  placed  longitudinally 
along  the  starboard  and  port  sides  of  the  float,  and  these  are  Well 
braced  together  by  crosspieces  connecting  the  top  and  bottom  chords 
of  the  trusses.  Another  truss,  but  smaller,  is  placed  at  the  bow  and 
connected  with  the  two  longitudinal  ones.  This  is  necessary  to 
support  the  turntable  upon  which  the  boom  rests.  In  Fig.  43  are 
shown  the  plan  and  elevation  of  the  steel  trusses  used  to  reinforce 
the  hull  of  the  dredge  "Chicago,"  as  given  in  Engineering  News,  Vol. 
XLV.  The  dimensions  of  the  hull  depend  to  a  great  extent  upon 
the  capacity  of  the  machine. 

To  prevent  the  dipper  dredge  from  tilting  under  the  great  strain 
of  the  work,  the  hull  is  provided  with  three  and  sometimes  even 

151 


152 


A  TREATISE    ON   DREDGES   AND   DREDGING 


four  spuds.  These  are  heavy  square  beams  which  are  sunk  into 
the  ground  so  as  to  firmly  support  the  float  in  the  same  manner 
as  the  legs  of  a  table.  Spuds  have  been  used  for  many  years,  as 
evidenced  by  the  machine  described  by  Mr.  Hachette,  employed 
at  Venice,  which  is  really  the  prototype  of  the  dipper  dredge. 

Spuds  may  be  either  vertical  or  inclined;  in  the  latter  case  they 
rest  on  the  banks  of  the  canal  to  be  excavated  by  the  dredge,  and 
are  called  bank  spuds.  They  are  used  only  on  dredges  of  small 
capacity  when  employed  in  the  excavation  of  small  and  shallow 
canals.  (Fig.  44.)  Vertical  spuds  are  very  important  on  dredges 


Outside  Line  of  Boat 


Plan 


Elevation. 


FIG.  43. — Plan  and  Elevation  of  Steel  Trusses  Reinforcing  the  Hull  of  the  Dredge 

"Chicago." 

of  large  capacity  and  then  they  are  operated  by  special  engines. 
As  a  rule  dredges  are  provided  with  three  spuds — two  of  them 
located  at  the  bow  either  side  of  the  frame  supporting  the  boom, 
and  these  are  of  larger  dimensions  than  the  spuds  at  the  stern. 
Thus  for  instance  the  dredge  "  Chicago  "  was  provided  with  three 
spuds,  each  of  the  two  forward  ones  being  composed  of  a  single 
stick  of  Oregon  fir  40X40  in.,  55  ft.  long.  The  stern  spud  was 
of  white  oak  24X22  in.,  55  ft.  long.  To  facilitate  the  penetration 
of  the  spuds  into  the  ground  their  lower  end  is  provided  with  heavy 
castings.  The  raising  and  lowering  of  the  spuds  is  done  by  means 
of  steel  wire  ropes  passing  over  sheaves  and  controlled  by  special 


154  A  TREATISE   ON  DREDGES   AND   DREDGING 

engines.  The  rope  for  lowering  the  spuds  passes  over  a  grooved 
sheave  fixed  at  the  top  of  the  spud,  and  its  free  end  is  fastened  to 
the  forward  side  of  the  spud  casting.  The  rope  for  raising  the  spud 
is  also  attached  to  the  forward  castings  and  passes  around  the  sheave 
in  a  slot  close  to  the  foot  of  the  spud.  The  other  ends  of  the  rope 
are  attached  to  opposite  ends  of  the  drum  of  the  spud  engine.  The 
spud  at  the  stern  is  operated  by  a  rope  fastened  to  the  bottom  of  the 
spud  and  passing  over  a  sheave  on  deck  and  thence  to  the  drum  of 
another  engine. 

The  dredging  apparatus  consists  of  a  steam  shovel  proper  of 
large  dimensions  and  made  up  as  usual  of  an  A  frame  supporting 
a  swinging  boom  with  its  dipper  handle  and  bucket. 

The  A  frame  is  composed  of  two  slanting  beams  firmly  fixed  to  the 
keelson  of  the  hull  and  resting  on  top,  one  against  the  other,  thus 
forming  a  truss  in  the  shape  of  the  letter  A.  This  frame  is  a  little  in- 
clined toward  the  front  and  it  is  held  in  position  by  iron  rods  or  back- 
stays provided  with  turnbuckles  fixed  to  the  stem.  In  dredges  of  small 
capacity  the  A  frame  is  generally  composed  of  two  simple  wooden 
beams,  but  in  dredges  of  larger  capacity  the  frame  is  made  of  two 
built-up  iron  beams  so  as  to  form  a  very  stiff  and  solid  structure. 
The  top  of  the  A  frame  is  always  furnished  with  a  gudgeon  pin  around 
which  swings  the  iron  rod  supporting  the  top  of  the  boom.  According 
to  the  capacity  of  the  dredge  the  A  frame  is  made  of  different  heights, 
varying  from  16  or  20  ft.  in  the  smallest  up  to  75  ft.  in  dredges  of 
large  capacity. 

The  boom  or  jib  is  a  heavy  trussed  steel  beam  with  a  long  slot 
in  the  middle  kept  in  an  inclined  position  by  iron  rods,  holding  its 
upper  end  to  the  top  of  the  A  frame,  while  its  lower  end  rests  on  a 
revolving  table.  The  trussed  beam  forming  the  boom  is  usually 
made  with  the  lower  chord  straight  and  the  upper  one  curved  or 
vice  versa,  but  in  very  large  dredges  to  make  the  boom  more  solid 
and  stiff  and  in  better  condition  to  support  the  weight  of  the  loaded 
bucket,  the  boom  is  built  up  with  curved  top  and  bottom  chords. 
The  length  of  the  boom  varies  with  the  capacity  of  the  dredge  and 
it  is  made  of  different  lengths,  varying  from  20  to  50  ft.  It  is  the 
swinging  of  the  boom  that  causes  the  bucket  to  revolve  in  a  large 
radius,  thus  covering  a  large  field  from  a  single  station. .  The  swing- 
ing of  the  boom  is  done  by  means  of  a  turntable  in  whose  center 
is  fixed  the  lower  end  of  the  boom.  The  turntable  is  built  up  of 
steel  plates  and  angles  and  is  supported  by  steel  wheels  moving 


DIPPER  DREDGES 

along  a  circular  track,  of  varying  diameter,  reaching  to  20  ft.  on 
the  larger  dredges.  The  turntable  is  provided  with  a  horizontal 
groove  around  which  passes  a  chain  or  rope  wound  around  the 
drum  of  a  reversible  engine.  By  paying  the  rope  in  or  out  the 
turntable  is  turned,  carrying  with  it  the  boom. 

The  dipper  handle  is  made  of  wood  reinforced  at  the  sides  with 
iron  wearing  plates.  In  small  dredges  the  lower  side  is  provided 
with  a  cog  rack  which  travels  on  pinions  mounted  on  the  boom. 
These  pinions  are  connected  with  a  wheel  controlled  by  a  brake  so 
that  the  dipper  can  be  held  in  any  position.  In  large  dredges  the 
dipper  handle  is  held  in  place  by  a  yoke  and  sliding  plates  arranged 
in  such  manner  that  it  can  be  held  in  any  desired  position.  The 
dipper  handle  is  inserted  in  the  slot  of  the  boom  and  it  is  made  of 
different  lengths,  depending  upon  the  depth  at  which  the  dredge 
is  designed  to  work. 

The  dipper  or  bucket  is  similar  to  the  one  used  on  steam  shovels. 
The  sides  are  built  up  of  heavy  steel  plates  riveted  to  angle  irons, 
while  the  bottom  is  only  hinged  to  the  back,  forming  a  trap  door, 
which  is  kept  closed  by  a  spring  latch.  The  latch  is  easily  opened 
by  simply  pulling  a  chain,  but  closes  automatically  as  soon  as  the 
dipper  is  lowered  again.  When  the  dredge  is  designed  to  work  in 
loose  soils  the  front  edge  of  the  bucket  is  reinforced  with  a  steel 
cutting  edge  which  can  be  easily  renewed  when  worn  out,  but  in 
dredging  through  compact  soils  the  front  edge  is  reinforced  by  steel 
projecting  teeth.  The  capacity  of  the  dredge  is  always  given  in 
terms  of  the  capacity  of  the  bucket,  thus,  for  instance,  a  6-cu.yd. 
dipper  dredge  is  a  dredge  of  the  dipper  type  in  which  the  capacity 
of  the  bucket  is  equal  to  6  cu.yds.  Fig.  45  shows  a  dipper  dredge 
of  6  cu.yds.  for  dredging  through  loose  soils,  built  by  the  Bucyrus 
Co.  of  South .  Milwaukee,  Wis.  Buckets  are  made  of  different 
sizes  varying  between  1  and  12  cu.yds.  A  bucket  of  6  cu.yds.  capac- 
ity seems  to  be  the  most  convenient  and  is  preferred  by  engineers 
and  contractors.  The  bucket  can  be  provided  with  a  heavy  cast- 
steel  bail,  or  the  boom  line  may  be  attached  directly  to  chains 
stretched  between  the  sides  of  the  bucket.  The  bucket  can  be 
fixed  to  the  handle  in  different  ways,  which  vary  with  the  different 
manufacturers.  The  boom  line  operating  the  bucket  is  attached 
to  the  bail,  passes  over  a  large  grooved  sheave  on  top  of  the  boom, 
and  passing  over  and  along  the  upper  side  of  the  boom  and  over  a 
second  large  grooved  sheave  on  the  turntable,  is  wound  around  the 


156  A  TREATISE   ON   DREDGES   AND   DREDGING 

large  drum  of  a  reversible  hoisting  engine.  The  line  can  be  either 
of  chains  or  steel  wire  cables,  the  latter  being  preferred,  owing  to 
the  lighter  weight  and  less  friction,  which  means  less  wear. 

The  various  engines  necessary  for  the  operation  of  the  dipper 
dredge  are  the  main  hoisting  engine,  the  swinging  engine,  the 
engine  for  the  spuds,  and  an  engine  for  the  dynamo.  The  main 
hoisting  engine  is  usually  of  the  double-cylinder,  double-drum, 
reversible  type  and  is  located  on  the  main  deck  forward.  The  swing- 
ing engine  also  is  located  forward  and  of  the  double-cylinder,  double- 
drum  reversible  type.  The  spuds  can  be  operated  by  a  single  or  two 
separate  engines,  the  former  is  preferred,  but  in  very  large  dredges 


FIG.  45. — Dipper  Dredge  of  6  cu.yds.  Capacity. 

the  two  forward  spuds  are  operated  by  a  double-drum  reversible 
engine,  and  the  aft  spuds  by  a  single-drum  reversible  engine,  or  all 
the  three  or  four  spuds  by  a  3-  or  4-drum  reversible  engine. 
An  engine  is  also  required  for  the  dynamos,  since  the  dredge  is 
lighted  by  electricity  and  arc  lamps  are  provided  on  deck  so  as  to 
dredge  even  at  night.  Steam  for  the  various  engines  is  provided 
by  a  marine  boiler  located  near  the  stern.  Boiler,  water  tanks, 
coal  bunkers  and  some  of  the  engines  are  placed  aft  so  as  to  counter- 
act the  weight  of  boom  with  the  heavy  bucket  when  the  dredge  is  in 
operation,  notwithstanding  it  is  firmly  fixed  to  the  ground  by  means 
of  spuds. 

All  the  various  dredging  operations  are  controlled  by  a  man  who 


DIPPER  DREDGES  157 

operates  the  different  engines  by  means  of  levers,  all  located  in  the 
captain's  room  on  deck.  The  dipper  dredges  of  large  capacity  are 
usually  provided  with  a  deckhouse  containing  the  kitchen,  dining- 
room,  sitting-room,  staterooms,  bathroom  and  office;  but  these 
conveniences  vary  in  class  of  work  done. 

The  dipper  dredge  is  a  stationary  machine  and  consequently 
is  entirely  without  propelling  apparatus  or  engine.  It  is  able,  however, 
to  move  from  place  to  place  so  as  to  follow  the  progress  of  the  work 
without  any  help  from  tugboats  or  from  the  anchoring  chains. 
When  the  dredge  is  to  be  moved  so  as  to  attack  a  new  bed,  the 
spuds  are  lifted,  the  dipper  handle  fully  extended  is  lowered  so  as 
to  engage  the  soil  as  in  dredging,  the  handle  is  then  withdrawn  and 
this  effort  causes  the  vessel  to  move  forward.  By  repeating 
the  same  operation  the  machine  slowly  advances  to  the  required 
point.  Then  the  spuds  are  lowered  again,  the  boat  is  made 
firm  and  the  dredging  operations  are  resumed.  It  takes  less  than 
two  minutes  to  lift  the  spuds,  to  move  to  a  new  place  to  be  dredged 
and  lower  the  spuds  again.  The  machine  can  be  moved  also  laterally 
by  rotating  around  one  spud.  This  is  done  by  the  stern  spud  being 
held  fast  to  the  bottom  while  the  two  others  are  lifted;  the  vessel 
will  move  either  to  the  right  or  the  left  by  the  same  operation  of  the 
dipper  engaging  the  soil,  then  the  stern  spud  is  lifted  while  one  of 
the  fore  spuds  is  lowered,  and  the  dredge  rotating  now  around  this 
new  point  will  be  moved  laterally ;  and  repeating  the  same  operation 
over  and  over  the  dredge  can  be  moved  the  required  distance,  when 
all  the  spuds  will  be  lowered,  the  machine  made  fast,  and  the 
dredging  resumed. 

The  output  of  the  dipper  dredge  is  an  average  of  one  bucket  per 
minute,  and  for  this  reason  contractors  have  continuously  requested 
manufacturers  to  increase  the  capacity  of  the  bucket.  Thus  there 
are  to-day  dredges  with  buckets  of  15  cu.yds.,  but  the  great  cost  of 
these  mighty  machines  and  their  high  running  expenses  so  increase 
the  cost  of  excavation  that  the  work  of  these  dipper  dredges  cannot 
be  compared  with  that  of  other  large  machines  of  different  type. 
However,  dipper  dredges  of  small  capacity  working  under  certain 
conditions  are  still  considered  the  most  efficient  and  economical 
machines. 

The  output  of  the  dipper  dredge  assumed  at  the  rate  of  one 
bucket  per  minute  gives  a  fair  idea,  for  rough  estimates,  of  the  work 
to  be  obtained  from  the  dipper  dredge  under  ordinary  circumstances. 


158  A  TREATISE   ON  DREDGES   AND   DREDGING 

There  are  numerous  conditions  which  tend  to  greatly  alter  this 
estimate,  and  that  must  be  considered.  The  presence  of  stumps 
and  boulders  in  the  ground  will  retard  the  work  of  the  dipper  dredges. 
Working  through  plastic  and  sticky  clay  the  progress  is  retarded, 
owing  to  the  fact  that  the  clay  sticks  in  the  bucket  for  some  time 
after  the  door  is  opened  before  it  falls  through.  A  dipper  dredge 
employed  to  dig  canals  through  marshy  land,  cutting  its  own  way 
and  depositing  the  debris  on  both  sides  so  as  to  form  the  ditches, 
will  do  a  larger  amount  of  work  than  if  used  in  places  in  which  the 
debris  is  placed  in  scows.  The  handling  of  scows  by  tugs  frequently 
causes  delays,  similar  to  those  caused  by  trains  in  steam-shovel 
work.  Then,  too,  less  work  is  done  when  only  a  few  feet  of  exca- 
vation is  necessary. 

The  following  examples  serve  to  illustrate  the  work  dipper 
dredges  will  do.  In  one  section  of  the  Chicago  Drainage  Canal 
five  dipper  dredges  of  2  cu.yds.  capacity  were  employed  for  dredging 
through  hard  clay.  The  best  week's  work  for  four  dredges  was 
an  average  of  1070  cu.yds.  per  10-hour  shift,  while  one  dredge 
reached  an  average  of  1530  cu.yds.,  thus  obtaining  an  average  effi- 
ciency of  nearly  one  bucket  per  minute.  Capt.  D.  C.  Kingman,  U.  S. 
Engineer  Corps,  reports  that  at  Sodus  Bay,  N.  Y.,  with  the  Osgood 
Dredge  "  Frontenac  "  1J  cu.yds.  dipper,  from  June  26  to  30, 1892,  in 
45  hours  of  actual  work  4390  cu.yds.  of  sand  and  gravel  were  dug, 
an  average  of  97  cu.yds.  per  hour,  or  about  one  bucket  per  minute. 
On  the  Raritan  River,  N.  J.,  the  dredge  "Alpha,"  with  a  dipper  of 
1  cu.yd.  capacity,  armored  with  teeth  so  as  to  work  through  rock, 
in  the  month  of  September,  1889,  working  207  hours,  excavated 
12,050  cu.yds.  of  shale  rock  and  gravel;  it  averaged  60  cu.yds.  per 
hour  and  consequently  at  the  rate  of  one  bucket  per  minute. 

In  Engineering  News,  February  28,  1901,  a  report  is  given  of  the 
trial  of  the  dredge  "  Chicago, "  with  an  8-cu.yd.  dipper,  working  in 
sand  and  clay  in  25  ft.  of  water,  excavating  in  30  minutes  385  cu.yds. 
of  material.  This  would  represent  12  cu.yds.  per  minute,  or  one 
bucket  and  a  half.  But  it  was  on  a  trial  performance  and  not  on 
regular  work,  being  a  new  machine  working  only  half  an  hour. 
However,  it  is  fair  to  assume  from  this  that  large  dredges  can  dig  a 
dipper  full  per  minute. 

The  output  of  the  dipper  dredge  depends  also  upon  the  locality 
in  which  the  machine  is  working.  For  instance  the  output  of  dredges 
working  in  wide  rivers  or  bays,  where  they  are  not  interfered  with 


DIPPER  DREDGES  159 

• 

by  passing  boats  or  scows  is  certainly  greater  than  in  dredges  com- 
pelled to  work  in  narrow  spaces  and  under  crowded  conditions. 
The  five  dredges  employed  in  the  section  of  the  Chicago  Drainage 
Canal,  mentioned  above,  while  in  the  best  week's  work  their  output 
was  almost  equal  to  one  bucket  per  minute,  yet  in  the  average  their 
efficiency  was  of  one  bucket  every  two  minutes,  owing  to  the  fact  that 
they  were  too  crowded  and  consequently  often  they  interfered  with 
one  another,  and  they  were  served  by  scows  and  tugboats.  When 
the  dredging  work  is  depending  upon  other  operations  it  would  be 
impossible  to  expect  the  greatest  efficiency  from  the  dredge.  Thus 
while  the  dredge  "Alpha,"  on  the  Raritan  River,  could  remove  shale 
rock  and  gravel  at  the  rate  of  one  bucket  per  minute,  yet  when  the 
rock  was  so  hard  that  it  was  necessary  to  recourse  to  blasting,  the 
same  dredge  on  the  same  locality  worked  at  the  rate  of  one  bucket 
every  nine  minutes. 

The  dipper  dredge  of  small  capacity  is  handled  by  a  crew  of 
6  men,  while  this  number  increases  with  the  capacity  of  the  machine, 
and  a  dredge  of  8  cu.yds.  is  served  by  16  men.  The  daily  running 
expenses  of  working  the  machine  are  wages,  coal,  water  and  oil 
and  waste.  Dividing  by  the  number  of  cu.yds.  dredged  the 
cost  per  one  cu.yd.  is  given.  Other  costs  to  be  considered  are  the 
interest  of  the  capital  invested,  the  wear  and  tear,  and  sinking  fund, 
but  these  will  be  discussed  in  a  special  chapter.  These  are  so  impor- 
tant that  while  in  the  Massena  Canal  a  dredge  worked  at  the  average 
cost  of  4  cents  per  cu.yd.  for  labor  and  coal,  the  cost  for  interest  and 
depreciation  was  7  cents  per  cu.yd.,  thus  making  a  total  cost  of  11 
cents  per  cu.yd.  The  other  items  were  almost  double  the  cost  of 
labor  and  coal. 

The  dipper  dredge  is  the  typical  American  dredge,  and  has 
rendered  magnificent  services  on  the  Great  Lakes.  But  even  to-day, 
notwithstanding  there  are  so  many  powerful  dredges  at  our  disposal, 
the  old-time  dipper  dredge  of  small  capacity  can  be  still  considered 
without  a  rival  on  small  contracts  for  the  improvement  of  narrow 
rivers  and  in  digging  canals  for  draining  purposes  when  the  debris 
is  deposited  on  both  sides  to  form  the  levee.  The  dipper  dredges  of 
small  capacity  are  handled  by  a  few  men,  are  not  easily  broken, 
and  the  repairs  are  almost  insignificant,  while  in  dredges  of  larger 
capacity  the  expenses  are  heavy  when  the  machine  is  compelled 
to  lay  idle  for  repairs.  Mr.  Robinson  says  that  a  wooden  dredge 
ten  years  old,  costing  say  $30,000,  will  excavate  1500  to  2000  cu.yds. 


160  A  TREATISE  ON  DREDGES  AND  DREDGING 

in  10  hours  with  a  crew  of  6  men  and  3  tons  of  coal.  With  such  a 
machine,  he  adds,  the  marvel  is  not  that  American  contractors  do 
not  use  the  big  and  costly  European  ladder  dredges,  but  that  these 
useful  American  machines  do  not  find  a  wider  recognition  in  Europe 
and  abroad. 


CHAPTER  XX 

) 

DIPPER   DREDGES 

THE  following  description  of  the  dipper  dredge  "Independent" 
condensed  from  an  article  in  the  Engineering  Record,  June  1, 
1907,  serves  to  illustrate  one  of  these  dredges  of  medium  size  with 
a  bucket  of  4J  cu.yds.  capacity. 

The  dredge  "  Independent/'  Fig.  46,  owned  by  the  Bush  Terminal 


FIG.  46.— The  Dipper  Dredge  "  Independent." 

Co.  of  New  York,  and  used  in  the  extension  of  its  docks  in  South 
Brooklyn,  was  built  especially  for  slip  work.  The  hull  is  90  X38  ft.  2 
in.,  by  12  ft.  deep,  and  unusually  heavy.  The  house  is  52X28  ft., 
containing  an  engine-room,  crew's  dining-room,  officers'  dining-room, 

161 


162  A   TREATISE  ON    DREDGES   AND   DREDGING 

kitchen,  washroom  and  toilet.  On  the  upper  deck  forward  is  the 
operating-room  and  three  cabins  for  the  captain,  engineer,  and 
steward.  On  the  upper  deck,  aft,  is  a  16X16  ft.  bunkhouse  for 
eight  men.  All  the  rooms  are  heated  by  steam. 

The  main  hoisting  engine  is  of  the  double-cylinder,  double-drum 
type,  placed  on  the  main  deck  forward.  The  bedplate  is  extended 
in  front  and  carries  the  inner  bearings  of  the  large  spur  wheels. 
These  wheels  are  thus  made  an  integral  part  of  the  engine  and  the 
maintenance  of  a  proper  relation  between  the  pitch  lines  of  the  spur 
wheels  and  the  pinions  on  the  main  crankshaft  is  assured.  The  engine 
cylinders  are  16X18  in.  The  drums  are  all  actuated  by  cork- 
inserted  frictions.  These  frictions  are  the  standard  Lidgerwood  type, 
made  of  hard  wood  turned  to  a  truncated  cross-section  and  working 
against  a  female  surface  of  turned  cast  iron.  Three-quarter  inch 
holes  on  2-in.  centers  were  bored  in  the  faces  of  the  wood  and  corks 
pressed  into  them.  The  holes  are  staggered  so  that  the  corks  cover 
the  whole  metal  surface  of  the  female  section  as  the  friction  revolves. 
It  is  stated  that  the  cork  surface  about  doubles  the  holding  power 
of  the  friction  and  maintains  the  grip  even  if  grease  gets  on  the 
surfaces.  It  is  believed  that  this  is  the  first  time  cork  inserts  were 
used  in  dredge  work. 

In  the  hold  is  the  backing  drum,  operated  by  a  wheel  which 
meshes  into  one  of  the  large  spur  wheels  of  the  main  drums.  The 
friction  of  these  three  drums  is  set  up  by  steam  nips  built  with 
wrought-iron  toggle  levers  and  actuated  by  an  Osgood  patent  steam 
grip  cylinder.  The  form  of  this  grip  is  novel.  The  thrust  on  the 
main  drums  and  backing  drum  is  transmitted  from  the  thrust  collar 
to  the  drum  through  a  special  roller  bearing  made  by  the  Philadelphia 
Roller  Bearing  Co.  These  were  adopted  to  reduce  the  frictional 
losses  incident  to  the  ordinary  arrangement  and  also  avoid  the 
cutting  of  a  keyway  through  the  main  shaft.  They  have  proven 
very  satisfactory. 

A  double-cylinder,  10  X  12-in.  engine  is  placed  in  the  hold  forward 
and  the  fore  and  aft  spuds  on  both  port  and  starboard  sides  are 
operated  by  it,  through  friction  drums.  The  spur-wheel  shaft 
extends  clear  across  the  hold.  Near  each  end  it  has  a  pinion  which 
engages  two  spur  wheels,  one  on  each  side  of  the  shaft,  each  of  which 
is  connected  with  a  friction  drum.  These  four  drums  carry  chains 
leading  to  the  four  spuds.  At  the  extreme  ends  of  the  main  shaft 
are  bevel  gears  through  which  power  is  transmitted  to  two  forward 


DIPPER  DREDGES  163 

gypsy  winches  on  the  main  deck.  The  two  stern  gypsy  winches  are 
operated  by  a  separate  6^  X  9-in.  double-cylinder  engine,  the  power 
being  transmitted  through  bevel  gears  as  for  the  forward  winches. 
All  the  speed  drums  and  their  gearings  are  interchangeable.  This 
includes  four  drums,  their  shafts,  frictions  and  other  details,  the 
bevel  gear  wheels  and  pinions  operating  the  capstans  and  the  capstans 
themselves.  This  reduces  to  a  minimum  the  possibility  of  delays 
and  cost  in  making  repairs  in  case  of  breakdowns,  making  it 
possible  to  be  ready  for  repairs  by  carrying  in  stock  only  one 
spare  piece  of  each  of  the  parts  subject  to  the  greatest  risk  of  breakage. 
For  instance,  the  level  pinions  are  intentionally  selected  as  the  break- 
ing pieces  for  the  capstan  gear.  There  are  four  of  these,  yet  only 
one  carried  in  stock  allows  quick  repairs  to  be  made. 

The  boiler  is  of  the  Scotch  marine  type,  11  ft.  in  diameter,  12 
ft.  long  and  has  two  42-in.  corrugated  furnaces.  There  are  three 
4000-gal.  steel  water  tanks  in  the  hold,  one  on  each  side  and  one 
near  the  stern.  The  last  is  always  kept  full  as  a  reserve  supply  and 
for  ballast.  There  are  two  double-cylinder  Blake  steam  pumps, 
one  for  the  boiler  feed  and  the  other  to  pump  from  the  bilge,  from 
a  water  boat,  or  from  the  tanks. 

The  boom  is  built  of  angles,  cover  plates  and  lattice  bars  in  the 
usual  manner,  and  is  53  ft.  2  in.  long  over  all.  The  head  sheaves  are 
attached  by  a  specially  designed  compact  universal  joint  which 
gives  the  wheel  freedom  of  motion  in  every  direction  and  prevents 
the  breakage  of  the  flanges,  which  sometimes  occurs  when  a  less 
flexible  connection  is  used.  The  leads  from  the  tip  of  the  boom  to 
the  top  of  the  A  frame  are  attached  to  the  latter  by  a  ball-and-socket 
joint.  This  joint  is  in  effect  as  if  the  two  leads  me^  at  one  point. 
Torsional  strains  in  the  boom  are  thus  avoided  when  the  boom  swings 
to  one  side  or  the  weight  on  the  lifting  chains  is  unequal.  The 
four  guy  cables  are  l|-in.  plow  steel.  The  dipper  is  of  the  usual 
type  and  the  58  ft.  handle  is  made  of  a  16X16  in.  Oregon  fir  stick, 
and  four  6X6Xj-in.  angles.  The  handle  is  built  under  the  Howard 
patent.  The  four  angles  of  the  timber  are  reinforced  by  6X6X-J- 
in.  angle  irons  riveted  through  and  through. 

The  turntable  is  carried  by  eight  conical  wheels  attached  to  the 
movable  or  upper  plate  and  rolling  on  a  fixed  circular  track.  The 
horizontal  thrust  is  taken  by  twelve  vertical  cylindrical  rollers, 
equally  spaced  about  the  circumference  of  the  moving  plate  and 
attached  to  it.  These  rollers  bear  against  the  outside  of  the  same 


164 


A  TREATISE  ON  DREDGES   AND   DREDGING 


rail  that  carries  the  weight.  This  turntable  is  operated  with  much 
less  power  than  those  of  the  usual  type  where  the  friction  is 
sliding.  The  wheels  can  be  removed  without  unshipping  the  turn- 
table. 

The  operating  room  is  arranged  so  that  the  captain  can  control 
all  the  movements  of  the  dredge  without  moving  from  his  position. 
He  can  also  control  the  forward  gypsies,  but  those  aft,  operated 
by  a  separate  engine,  are  manipulated  by  the  crew. 

The  dredge  is  equipped  with  an  electric  lighting  plant,  current 
for  which  is  generated  by  a  7J-K.W.  General  Electric  generator 
direct  connected  to  a  small^  vertical  engine.  The  wiring  is  carried  in 


FIG.  47. — Dipper  Dredge  "  Majestic." 

loricated  conduit  as  in  government  naval  works.  A  special  system 
of  piping  with  hose  connections  is  provided  for  fire  protection,  the 
bilge  and  tank  pump  being  arranged  so  that  it  can  pump  salt  water 
for  this  purpose. 

The  " Independent"  was  designed  by  Mr.  W.  H.  Arnold,  chief 
engineer  of  the  Bush  Terminal  Co.,  the  engineers  of  the  Lidgerwood 
Mfg.  Co.  co-operating  in  the  detail  designing  of  some  features. 

This  description  of  the  dredge  "  Majestic,"  Fig.  47,  slightly  con- 
densed from  a  paper  published  in  the  Engineering  News,  February 
7,  1907,  will  serve  to  illustrate  a  dipper  dredge  of  large  capacity: 

The  dredge  "Majestic  "  built  for  use  on  the  improvement  of  the 
West  Neebish  channel  in  the  St.  Mary's  River,  Michigan,  has  a  num- 


DIPPER  DREDGES  165 

0 

ber  of  points  of  special  interest,  but  its  two  prominent  features  are 
the  following:  First,  it  is  powerful  enough  to  dredge  solid  beds  of 
soft  limestone  rock  without  blasting,  and  second,  loss  of  time  and 
money  due  to  the  renewal  of  worn  and  broken  main  cables  is  greatly 
reduced  by  the  use  of  a  drum  which  enables  500  or  1000  ft.  of  cable 
to  be  held  in  reserve  instead  of  using  and  renewing  cables  of  the 
regular  working  length. 

The  hull  is  of  steel,  116X40  ft.  and  13  ft.  deep,  with  two  steel 
trusses  24  ft.  deep  extending  the  entire  length.  The  trusses  are 
built  of  12-in.  channels  and  I-beams.  The  boom  is  of  steel  construc- 
tion, 60  ft.  long,  stepped  into  a  steel  casting  at  the  bow  and  supported 
by  four  cables  2J  in.  diameter  leading  from  the  top  of  a  40-ft.  A  frame 
stepped  on  top  of  the  anchor  slides.  Two  of  those  cables  take  the 
strain  and  the  other  two  act  as  safety  cables.  The  boom  is  swung 
by  a  pair  of  2-in.  cables  on  a  24-ft.  turntable  or  swinging  circle  with 
arms  extending  on  each  side  of  the  boom.  These  cables  are  wound 
on  a  40-in.  drum,  compound  geared  to  a  pair  of  separate  engines, 
with  cylinders  10X14  in.  These  engines  are  set  on  the  hurricane 
deck  and  this  arrangement  gives  the  cables  a  straight  head  from 
the  drum  to  the  swing  circle.  The  dipper  handle  is  54  ft.  long  from 
back  of  dipper,  and  weighs  15  tons;  with  a  5-ft.  dipper  it  will 
excavate  to  a  depth  giving  30  ft.  of  water.  The  sheaves  for  the  fl\- 
dipper  cable  are  8  ft.  in  diameter  and  are  of  built-up  construction; 
the  hub,  3  ft.  long,  is  of  cast  iron,  bushed  with  a  bronze,  which  runs 
loose  on  a  9-in.  shaft.  The  spoke  section  is  a  steel  casting,  keyed  to 
the  cast-iron  hub;  the  rim  is  also  a  steel  casting  and  bolted  to  the 
spokes. 

The  dipper  is  handled  by  a  horizontal  engine  of  250  H.P.  capable 
of  exerting,  through  the  gearing,  a  pull  of  200  tons  upon  the 
dipper  cable.  The  engine  has  two  cylinders,  16X20  in.,  and,  as  in 
many  large  dredges,  cables  are  used  instead  of  chains.  The  engine 
drives  the  differential  cable  drum,  4  ft.  and  6  ft.  diameter,  through 
compound  gearing,  requiring  19  revolutions  of  the  engine  to  effect 
one  revolution  of  the  drum. 

The  cable  drum  is  of  special  design,  invented  and  patented  by 
Mr,  W.  S.  Edward,  having  as  its  principal  feature  an  extension  for 
about  800  ft.  of  cable  in  addition  to  the  200  ft.  working  length, 
so  that  a  single  cable  1000  ft.  long  is  carried;  with  the  ordinary 
arrangement  the  dredge  would  have  a  hoisting  cable  about  180  ft. 
long,  and  when  this  was  broken  the  entire  cable  would  have  to  be 


166  A  TREATISE  ON  DREDGES  AND  DREDGING 

renewed,  as  these  cables  usually  break  at  about  80  ft.  from  the 
outer  end  and  the  remainder  is  then  too  short  for  further  use.  With 
the  Edward  storage  drum,  a  cable  1000  ft.  long  is  used,  and  when 
this  breaks  only  about  80  or  90  ft.  are  lost,  the  working  length  being 
restored  by  paying  out  sufficient  cable  from  the  storage  part  of  the 
drum. 

The  drum  and  gears  are  all  open-hearth  steel  castings.  All 
friction  belts  are  operated  by  compressed-air  cylinders,  the  air 
at  170  Ibs.  pressure  being  furnished  by  two  Westinghouse  air  pumps 
arranged  tandem. 

The  bow  spuds  are  of  great  size,  43  in.  square  and  52  ft.  long. 
Each  is  composed  of  four  22-in.  sticks  dressed  on  all  sides  to  21 J  in.; 
these  are  fitted  into  a  cast-steel  shoe  at  the  bottom  and  bolted  together 
for  8  ft.  from  the  bottom  with  24  bolts  1J  in.  in  diameter.  There 
are  no  bolts  above  these,  being  held  together  by  an  iron  band 
f  XlO  in.,  so  that  the  individual  sticks  have  a  certain  amount  of 
spring  or  movement.  In  the  top  of  the  shoes  is  a  9J-in.  hole  for 
a,  9-in.  shaft,  10  ft.  long,  which  is  secured  to  the  spud  foot  by  six 
2-in.  and  2J-in.  staples  with  jam  nuts  on  the  ends.  The  spud  foot 
is  of  timbers  16  in.  square,  bolted  together  with  eight  2-in.  bolts 
10  ft.  long,  the  size  of  the  foot  being  10x12  ft.  The  purpose  of 
this  is  to  prevent  the  spuds  from  sinking  into  the  bottom  when  the 
dredge  is  lifted  up  on  the  spuds,  when  working  in  soft  material.  The 
dredge  can  be  lifted  about  2  ft.  above  its  floating  position  and  this 
is  accomplished  by  means  of  a  2-in.  cable  running  over  the  top 
of  each  spud  on  a  sheave  and  fastened  to  the  spud  slide.  The  great 
weight  will  then  force  the  spuds  from  2  to  6  ft.  into  the  bottom, 
but  the  broad  feet  then  keep  the  dredge  steady  while  in  operation. 
The  spud  and  foot  are  also  raised  by  means  of  a  2-in.  cable  running 
over  a  sheave  which  is  fastened  to  the  cast-steel  shoe  and  is  operated 
by  a  cable  and  a  hoisting  drum  driven  from  the  main  engine  through 
a  friction  band  and  drum.  The  stern  spud  is  a  single  28-in.  timber, 
55  ft.  long,  operated  by  rack  and  pinion.  The  spud  slides  in  a  heavy 
fixed  shoe  which  carries  the  pinion  on  the  front  face  and  two  bearing 
rollers  at  the  rear  face  of  the  spud.  The  pinion  is  compound  geared, 
and  driven  by  a  chain  of  forged  steel  links  and  roller  pins  from  a 
separate  engine  placed  below  the  deck,  the  chain  passing  through 
this  deck  to  the  countershaft  of  the  pinion  gear. 

This  dredge  was  built  to  excavate  the  approaches  to  the  rock 
cut  of  the  new  West  Neebish  Channel.  The  material  in  the  approaches 


DIPPER  DREDGES  167 

t 

and  the  rock  cut  consist  mostly  of  boulders  and  hardpan,  underlaid 
with  limestone,  shale  and  bed  rock.  The  bed  rock  varies  in  depth  from 
6  in.  to  14  ft.,  the  layers  being  in  some  places  4  ft.  thick.  A  25-ft. 
depth  of  water  is  required,  and  it  has  been  found  practicable  to 
secure  the  required  depth  with  this  dredge,  using  a  6-yd.  dipper 
which  weighs  (without  teeth)  over  11  tons;  there  are  four  teeth 
on  the  dipper,  weighing  800  Ibs.  each.  It  would  be  difficult  to  state 
the  working  capacity  of  the  dredge  in  rock,  as  the  latter  is  overlaid 
with  several  feet  of  boulders  and  earth,  all  being  dug  at  one  operation, 
but  the  capacity  is  estimated  at  from  40  to  50  cu.yds.  per  hour 
in  the  rock  alone.  The  capacity  in  soft  material  is  about  400  to 
500  cu.yds.  per  hour,  using  an  8-yd.  dipper.  The  cost  of  running 
this  machine  is  estimated  at  $30  per  hour. 

The  dredge  "  Majestic  "  was  built  from  plans  of  its  owners,  and 
has  proved  very  satisfactory  in  operation.  The  hull  and  boiler 
were  built  by  the  Manitowoc  Dry  Dock  Co.  of  Manitowoc,  Wis. 
The  boom  A  frame,  swinging  circle,  circle  sheaves  and  dipper  handle 
were  built  by  the  Bucyrus  Co.  of  South  Milwaukee,  Wis.  The 
three  sets  of  engines,  with  drums  and  gearing,  were  built  by  the 
Jackson  &  Church  Co.  of  Saginaw,  Mich.,  which  company  controls 
the  patents  for  the  Edward  cable-storage  drum  above  described. 


CHAPTER  XXI 
GRAB   DREDGES 

ANOTHER  intermittent  dredge  is  one  equipped  with  grab  buckets. 
This  machine  is  considered  one  for  great  depths,  as  it  is  able  to 
excavate  at  places  out  of  reach  of  any  other  machine.  The  ordinary 
grab  dredge  consists  of  a  steel  bucket  in  the  shape  of  a  grab,  capable 
of  picking  up  large  boulders  and  soft  materials  and  usually  worked 
by  a  steam  crane,  which  lets  the  open  grab  down  to  the  ground  to  be 
excavated  and  then  closes  it  by  a  chain,  which  forces  the  tines  into 
the  ground.  The  grab  is  then  raised  by  the  crane  and  the  contents 
are  deposited  on  the  sides  of  the  excavation  or  into  barges  to  be 
carried  to  the  dumping  place. 

The  grab  bucket  dredge  is  a  very  convenient  machine  and  can 
be  adapted  to  a  large  variety  of  work.  In  spite  of  its  simplicity  it 
is  a  useful  machine.  Any  contractor  can  easily  build  one  of  them. 
By  mounting  on  a  float  or  scow  any  locomotive  crane  or  derrick 
with  its  necessary  engines,  and  by  attaching  a  grab  bucket  to  the 
hoisting  rope  or  chain,  a  dredge  is  obtained.  A  machine  of  this  class 
does  satisfactory  work  on  the  improvement  of  small  harbors  and  rivers 
and  is  extensively  used  throughout  the  English  Colonies.  Besides 
the  common  use  of  dredging  the  bottom  of  canals,  rivers  and  harbors 
for  navigation  purposes,  the  grab  bucket  dredge  can  be  used  for 
digging  gold,  oysters,  pearls,  corals  and  sponges  from  great  depths. 
In  a  word  its  many  uses  make  it  a  very  convenient  machine. 

The  first  grab  dredge  built  was  perhaps  the  one  designed  by 
Fr.  Domenico  Ferra  and  used  at  Savona  in  1773;  but  the  machine 
as  now  used  was  first  constructed  and  extensively  used  in  America, 
and  then  introduced  into  England  and  her  Colonies.  There  is  a 
difference  between  the  grab  dredges  built  in  America  and  those 
constructed  in  England  in  the  mounting  and  handling  of  the  bucket 
as  well  as  in  the  capacity. 

The  American  grab  dredge  is  constructed  as  follows:  The 
machine  consists  of  a  strongly  built  A  frame  mounted  on  a  boat  and 

168 


GRAB  DREDGES  169 

• 

supporting  an  inclined  swinging  boom.  The  boom  rests  on  a  turn- 
table and  its  upper  end  is  able  to  revolve  around  the  gauging  pin 
of  the  A  frame,  being  kept  in  an  inclined  position  by  means  of 
iron  rods  furnished  with  turnbuckles.  One  or  two  sheaves  located 
at  the  top  of  the  boom  guide  the  chains  controlling  the  bucket.  The 
bucket,  made  of  steel,  is  divided  into  two  or  more  sections  provided 
with  lever  arms  and  chains  so  arranged  that  the  bucket  can  be 
closed  and  open  at  will.  The  chains  are  wound  around  the  drums 
of  hoisting  engines  placed  on  deck  of  the  boat,  and  as  the  bucket 
is  operated  by  two  chains  there  are  two  drums  on  the  hoisting  engine. 
Steam  power  is  supplied  to  the  engines  by  boilers  which  are  located 
at  the  stern  of  the  boat.  The  boat  is  built  of  rectangular  form  in 
the  shape  of  a  float,  with  a  structure  above  deck  to  house  the  boiler 
and  machines  and  in  some  cases  even  to  provide  accommodation  for 
the  crew.  While  the  machine  is  in  operation  the  boat  is  fastened 
to  the  bottom  by  three  or  four  spuds  which  are  constructed  and 
operated  as  with  the  dipper  dredge.  As  the  efficiency  of  the  machine 
is  considered  one  bucket  per  minute,  the  manufacturers  have  increased 
greatly  the  capacity  of  buckets  and  to-day  we  have  grab  dredges 
with  buckets  of  8,  10  and  12  cu.yds.  capacity. 

The  English  grab  dredge  consists  of  an  ordinary  locomotive 
crane  mounted  on  a  boat.  The  locomotive  crane  is  composed  of 
a  large  horizontal  cog-wheel,  whose  axis  is  fitted  into  a  socket  of 
an  iron  frame,  with  wooden  platform,  upon  which  are  placed  the 
boiler  and  the  engine.  In  front  of  the  iron  frame  there  is  a  jib  or 
boom  braced  by  means  of  iron  rods,  connected  to  vertical  iron 
stands,  and  tied  to  the  rear  of  the  frame  of  the  platform  by  rods 
provided  with  turnbuckles.  The  boom  or  jib  is  made  of  various 
designs  and  of  different  materials,  but  usually  it  is  made  of  iron 
except  when  very  long,  when  it  is  made  of  trussed  steel.  The  bucket 
is  attached  to  the  hoisting  chain,  which  after  passing  over  a  sheave 
at  the  top  of  the  boom  is  wound  around  the  drum  of  the  hoisting 
engine.  The  engine  is  so  arranged  that  by  putting  into  gear  another 
small  cogwheel  whose  cogs  engage  those  of  the  large  one  supporting 
the  platform,  the  platform  and  boom  and  consequently  the  bucket 
turn  a  complete  circle. 

The  English  grab  dredging  machine  is  mounted  on  many  kinds 
of  boats,  depending  upon  the  locality  of  the  work.  In  dredging 
along  the  quay  walls  or  small  harbors  and  also  along  canals  and 
rivers,  the  machine  is  mounted  on  any  ordinary  barge,  being  moved 


GRAB  DREDGES  171 

from  place  to  place  by  tugboats.  The  barge  can  be  made  in  the 
shape  of  wooden  floats  similar  to  those  used  in  America,  or  may  be 
constructed  in  the  shape  of  the  hull  of  a  boat  with  a  hold  amidship 
for  carrying  materials  or  goods.  The  dredging  apparatus  can  also 
be  mounted  upon  a  double  cylindrical  iron  pontoon,  as  is  done  on 
the  improvements  of  the  Nile  River.  When  the  dredge  is  employed 
on  work  where  the  materials  are  directly  deposited  along  the  sides 
of  the  excavation,  and  it  must  be  moved  continuously  from  place  to 
place  without  the  help  of  tugboats,  then  the  apparatus  is  mounted 
upon  a  self-propelling  boat.  The  propelling  apparatus  may  consist 
either  of  paddle  wheels  or  screw  propellers.  When  the  dredge  is 
moved  by  means  of  paddle  wheels,  as  a  rule,  only  one  wheel  at  the 
stern  of  the  boat  is  used,  while  the  dredging  machine  is  located 
at  the  bow.  In  such  cases  only  one  boiler  is  used  and  it  is  located 
in  the  hold  near  the  wheel,  the  steam  being  carried  to  the  hoisting 
engine  by  means  of  pipes.  A  machine  mounted  in  this  manner  is 
preferred  when  necessary  to  have  one  of  very  light  draft  and  small 
height,  so  as  to  navigate  readily  in  very  shallow  waters  and 
easily  pass  under  bridges.  The  boat  can  be  moved  also  by  ordinary 
screw  propellers.  Then  both  the  digging  and  propelling  apparatus 
are  mounted  at  the  stern.  The  boiler  is  located  either  on  the  turning 
platform  of  the  crane  and  the  power  for  the  propeller  is  transmitted 
by  means  of  gearing  and  shafting.  However,  the  propelling  and 
digging  apparatus  may  be  independent  of  one  another;  then  the 
machine  is  provided  with  two  sets  of  engines  and  steam  is  supplied 
by  a  stationary  boiler.  In  the  machines  of  this  type  the  crane 
with  the  digging  bucket  is  located  aft.  The  boat  can  be  constructed 
of  wood  or  iron  when  built  to  navigate  in  deep  waters  or  carry 
the  materials  outside  the  harbor.  The  boat  can  be  constructed 
with  a  hold  for  carrying  the  materials  or  with  hoppers  closed  by 
doors  at  the  bottom,  where  the  materials  are  temporarly  deposited 
in  order  to  be  transported  and  dumped  in  deep  waters.  Thus  the 
machine  will  act  like  any  other  hopper  dredge  of  any  type,  but  since 
the  efficiency  of  the  English  grab  dredge  is  very  limited,  the  hop- 
pers also  are  made  of  small  capacity,  very  seldom  exceeding  500  or 
600  tons.  These  machines  are  employed  in  the  English  Colonies, 
especially  Australia.  Fig.  48  represents  an  English  grab  bucket 
dredge  of  the  hopper  type  with  separate  boiler  and  propelling 
apparatus  as  used  in  harbor  works.  To  increase  the  efficiency  of 
the  machine  two  dredging  apparatus  are  used,  mounted  one  at  the 


172 


A  TREATISE   ON   DREDGES   AND   DREDGING 


stern  and  the  second  at  the  bow  of  the  boat ;  steam  being  provided 
by  a  stationary  engine  located  amidship.  This  type  of  dredge  is 
preferred  by  South  American  engineers  and  contractors  in  the 
improvements  of  harbor  and  rivers.  (Fig.  49.)  At  Liverpool  was 
once  employed  a  hopper  dredge  provided  with  four  grab  dredging 
apparatus  of  the  Priest  man  type. 

There  is  a  large  variety  of  buckets  used  on  a  grab  dredge,  but 
for  the  sake  of  classification  they  can  be  grouped  into  two  types, 
namely,  the  clamshell  and  orange  peel  buckets. 

The  clamshell  bucket  derives  its  name  from  its  shape, 
resembling  the  shell  of  a  clam.  The  scoop  or  bucket  is 
divided  into  two  segments  pivoted  at  their  upper  inner  corners 


r 


FIG.  49. — South  American  Grab  Dredge. 


and  is  supported,  raised  or  lowered  and  opened  or  shut  by  means 
of  chains  passing  to  proper  winding  drums  on  the  deck  of  the  boat. 
The  dipper,  when  in  motion,  in  old  machines,  was  steadied  by  a 
pair  of  long  poles  securely  fastened  to  it  and  passing  through  rings 
or  ears  fixed  at  proper  points  on  the  boom.  Improved  models  of 
buckets  have  made  the  guide  holes  unnecessary  for  dredging  pur- 
poses, although  this  .old  arrangement  is  still  found  on  dredges  of 
small  capacity. 

The  bucket,  as  a  rule,  is  constructed  of  two  steel  scoops,  pivoted 
together  at  their  upper  inner  corners,  arranged  so  as  to  open  and 
close  at  will,  and  forming  when  closed  an  ordinary  bucket  for  the 
raising  of  the  materials  from  the  bottom.  The  scoops  forming  the 
bucket  are  made  of  different  shapes,  depending  upon  the  quality 


GRAB  DREDGES  173 

f 

of  the  material  to  be  dredged.  When  the  scoops  are  made  of 
steel  plates  with  sharp  edges,  we  have  a  closed  solid  bucket 
convenient  for  working  through  such  loose  materials  as  quick- 
sand and  mud.  For  working  through  clay  a  bucket  in  which  the 
edges  of  the  scoops  are  provided  with  tines,  Fig.  50,  is  considered 
the  most  suitable.  For  dredging  through  hard  sandy  material 
the  edges  of  the  scoops  are  furnished  with  interlocking  tines  set 
close  together.  Finally  for  raising  boulders,  gravel,  and  blasted 
debris  an  open-tined  grab  is  used  built  in  the  manner  shown  in 
Fig.  51.  The  buckets  herewith  represented  are  those  constructed 
by  Messrs.  Rose,  Downs  &  Thompson,  Ltd.,  being  similar  in  their 
outlines  to  others  built  by  European  manufacturers.  In  America 


FIG.  50. — Grab  Bucket  for  Dredging  FIG.  51. — Grab  Buckets  for  Gravel 

through  Clay.  and  Boulders. 

only  the  solid  closed  bucket  is  used.  This  is  due  to  the  fact  that 
there  is  a  tendency  here  to  use  buckets  of  as  large  dimensions  as 
possible,  hence  the  penetration  into  the  soil  is  accomplished  by 
means  of  the  great  weight  of  the  bucket  itself,  instead  of  being  due 
to  the  shape  and  arrangement  of  the  tines  located  at  the  edges  of 
the  scoops. 

The  clamshell  bucket  has  an  overhead  iron  rectangular  frame. 
At  the  lower  end  of  this  frame  are  pivoted  the  two  parts  of  the  bucket, 
and  the  cross-head  piece  regulates  the  chains.  These  iron  frames, 
together  with  the  manner  of  attaching  the  two  parts  of  the  bucket 
to  the  frame,  and  the  device  for  opening  and  closing  the  bucket, 
form  the  chains  of  the  numerous  patents. 

Owing  to  the  fact  that  the  efficiency  of  the  machine  is  estimated 
at  one  bucket  per  minute,  American  contractors  have  rapidly 


174  A  TREATISE  ON  DREDGES   AND   DREDGING 

increased  the  size  of  grab  bucket  dredges.  Thus  in  the  grab  dredge 
used  at  Buffalo  Breakwater  and  described  in  the  following  chapter 
the  bucket  was  constructed  with  a  capacity  of  12  cu.yds.  English 
manufacturers  usually  build  buckets  of  four  sizes,  varying  from 
£  to  1  J'cu.yds.  capacity.  The  small  efficiency  of  the  English  machines 
compared  with  the  American  is  due  to  the  different  manner  in 
which  the  dredging  machines  are  mounted.  Handling  great 
weights  the  small  English  vessel  would  easily  capsize,  hence  the 
buckets  are  made  of  small  capacity. 

The  other  form  of  bucket  used  in  connection  with  the  grab 
dredge  is  the  orange  peel  bucket.  This  derives  its  name  from  the 
fact  that  when  the  bucket  is  closed  it  is  of  hemispherical  form  and 


FIG.  52. — Orange  Peel  Bucket,  Open.     FIG.  53. — Orange  Peel  Bucket,  Closed. 

closely  resembles  the  peel  of  half  an  orange.  The  bucket  consists 
of  three  or  four  triangular  blades  and  when  closed  forms  a  tight 
hemispherical  receptacle  for  the  excavated  materials.  When  open 
the  blades,  provided  with  steel  points,  resemble  sharp  spades  which 
are  well  adapted  for  penetrating  hard  materials.  The  blades  are 
so  adjusted  that  the  maximum  digging  effect  is  produced  with 
but  a  slight  tendency  to  lift  the  bucket  when  closing.  Horizontal 
arms  are  riveted  to  the  blades,  and  their  inner  ends  are  attached 
to  a  central  block,  while  the  outer  ones  are  hinged  to  vertical  connect- 
ing-rods, pivoted  at  their  upper  ends  to  the  upper  center  block. 
The  power  wheel  for  closing  the  bucket  is  fastened  to  the  lower 
central  block,  and  is  somewhat  eccentric  in  shape,  so  that  it  gives 
its  maximum  power  just  as  the  bucket  begins  to  close.  The  bucket 
is  well  braced,  and  the  shaft  is  extended  on  either  side  to  receive 


GRAB  DREDGES 


175 


the  cams  to  which  are  attached  the  power  chains.  The  capacity 
of  the  bucket  varies  from  1  cu.ft.  to  about  10  cu.yds.  Figs.  52  and 
53  represent  one  of  the  orange  peel  buckets  as  built  by  the  Hayward 
Company  of  New  York. 

The  orange  peel  bucket  is  seldom  used  for  dredging  purposes 
while  the  clamshell  bucket  seems  to  be  in  favor  with  engineers 
and  contractors.  However,  grab  dredges  with  orange  peel  buckets, 
are  used  in  the  improvements  of  small  rivers  in  which  the  dredged 
materials  are  deposited  on  both  shores.  For  such  work,  however, 
the  dipper  dredge  would  be  more  efficient  and  economical.  The 
grab  dredge  is  the  machine  for  great  depths,  and  it  is  only  under 
such  conditions  and  when  no  other  machine  could  be  employed 
that  the  grab  dredge  can  be  used  to  great  advantage. 

Grab  buckets,  both  clamshell  and  orange  peel,  are  now  designed 
to  pick  up  hard  materials,  such  as  rocks  and  stumps.  Some  of  the 
best  designs  will  hold  so  tenaciously  to  a  stump  as  to  pull  it  loose. 
The  fact  that  such  dredges  will  do  this  work  in  deep  water  means  a 
decided  advantage. 

The  bucket  of  the  grapple  dredge  can  be  operated  in  two  different 
ways — either  by  a  single  or  a  double  line.  When 
one  line  is  used  this  performs  all  operations  of 
opening,  closing,  raising  and  lowering  the  bucket, 
while  when  two  lines  are  employed,  one  is  for 
closing  and  hoisting  the  bucket  and  the  second 
for  opening  it. 

With  a  single  line,  it  passes  over  a  sheave  at 
the  top  of  the  boom  to  the  drum  of  the  hoisting 
engine.  The  chain,  after  passing  through  a  hole 
in  the  fixed  discharging  hook,  which  is  sus- 
pended from  the  boom  head,  is  wound  around 
and  fixed  to  a  sheave  within  the  bucket.  The 
operation  of  the  machine  is  very  simple;  the 
bucket  is  lowered  open,  and  the  action  of  raising 
closes  it.  When  raised  the  discharging  hook 
opens  the  bucket,  which  empties  and  is  then 
lowered  for  a  fresh  operation.  The  discharging 
hook  is  suspended  either  by  chains  or  wire 
ropes  or  by  bars;  in  either  case  they  are  capable  of  adjustment  so 
as  to  regulate  the  height  of  discharge.  There  is  on  the  market  a 
very  large  variety  of  discharging  hooks  which  together  with  the 


FIG.  54. — Cooper  & 
Holdsworth's  Sin- 
gle-chain Attach- 
ment. 


176  A   TREATISE  ON  DREDGES  AND   DREDGING 

attachment  of  the  hoisting  rope  form  the  claims  of  the  numerous 
patents,  which  are  generally  known  by  the  name  of  the  various 
inventors.  Fig.  54  shows  the  single-chain  attachment  to  a  whole- 
tine  bucket  of  the  Cooper  &  Holdsworth  patent. 

To  operate  the  dredging  bucket  by  the  single-line  method  seems 
at  first  simple  and  convenient.  But  when  it  is  considered  that  all 
the  strain  is  thrown  upon  only  one  line,  which  is  more  liable  to 
break  while  the  machine  is  working  and  possibly  when  the  bucket 
is  under  water,  thus  requiring  the  costly  assistance  of  divers  to 
recover  it,  this  method  has  decided  drawbacks.  Another  objection 
to  the  single-chain  method  is  the  fact  that  in  order  to  discharge 
the  bucket  it  is  necessary  to  raise  it  to  a  certain  fixed  height, 
regulated  by  the  distance  of  the  opening  gear  or  hook  from  the 
boom  head,  thus  when  a  false  lift  is  made  the  bucket  must  be 
brought  to  this  fixed  height  before  it  can  be  reopened.  A  favor- 
able consideration  is  that  a  single  line  does  not  require  a  special 
boom,  but  it  can  be  readily  attached  to  the  boom  of  any  existing 
crane. 

In  the  double-line  system  the  bucket  is  suspended  by  two  lines, 
one  called  the  closing  or  hoisting  line  and  the  other  the  opening  line. 
The  latter  is  held  in  tension  while  the  former  is  being  lowered,  and  can 
be  stopped  to  allow  the  dredgings  to  be  discharged,  this  being  done 
by  allowing  the  entire  weight  of  the  bucket  to  come  upon  the  opening 
line.  The  engine  operating  the  lines  can  be  provided  either  with 
one  or  two  drums.  In  the  latter  case  each  line  is  attached  to  its 
own  drum  and  its  movements  are  regulated  by  the  operators  by 
means  of  levers.  But  when  the  hoisting  engine  is  provided  with 
only  one  drum  the  opening  line  is  connected  by  a  series  of  sheaves 
to  a  weight  moving  in  a  vertical  slide  against  the  boiler.  As  the 
bucket  is  lowered  this  weight  is  raised,  thus  keeping  the  bucket 
open  by  the  tension  on  the  opening  line.  The  total  force  exercised 
upon  the  material  to  be  lifted  by  the  grapple  dredge,  being  the 
weight  of  the  bucket  plus  the  energy  of  descent,  it  follows  that 
in  this  kind  of  machine,  this  must  be  minus  the  effect  of  the  counter- 
weight, which  is  seldom  less  than  1  ton  and  for  deep  lifts  as  much 
as  4  tons.  By  avoiding  the  use  of  weights  to  take  up  the  slack 
of  the  opening  line,  the  whole  energy  of  the  bucket  in  its  descent 
is  available  to  excavate  the  material,  thus  enabling  a  greater  cut 
to  be  taken.  American  manufacturers,  as  a  rule,  build  only  grab 
bucket  dredges  provided  with  the  double-line  system,  each  ilne 


GRAB   DREDGES  177 

• 

being  controlled  by  a  drum  of  an  ordinary  double-cylinder-double- 
drum  reversible  engine. 

The  manner  of  operating  the  grab  bucket  by  means  of  the  double- 
line  system  is  very  simple.  When  the  bucket  is  lowered  to  its  work 
both  lines  run  out  freely,  being  kept  from  overrunning  by  a  brake; 
thus  the  full  energy  of  the  falling  bucket  is  employed  in  embedding 
itself  in  the  material  to  be  lifted.  As  the  bucket  can  be  opened  or 
closed  in  any  position,  in  submarine  works  in  case  the  bucket  becomes 
fastened  to  the  bottom,  it  can  be  instantly  opened  to  clear  itself 
and  another  lift  taken  without  further  raising  the  bucket. 

There  is  no  limit  to  the  depth  at  which  the  grab  bucket  dredge 
can  be  employed.  For  ordinary  navigation  purposes  a  depth  of 
30  to  35  ft.  is  the  limit  of  dredging,  but  at  such  a  depth  other  dredg- 
ing machines  will  give  perhaps  better  results.  It  is,  however,  in  deep 
dredging  that  the  grab  dredge  finds  its  greatest  usefulness ;  thus,  for 
instance,  the  dredging  for  the  Buffalo  breakwater  in  90  ft.  of  water 
was  very  successfully  done  by  the  clamshell  bucket  dredge  "Finn 
MacCool"  illustrated  in  the  following  chapter.  It  is  also  used  for 
sinking  cylinders,  shafts  and  digging  pearls,  corals  and  auriferous 
soils  from  great  depths. 


CHAPTER  XXII 
DESCRIPTIONS    OF    CLAMSHELL    DREDGES 

THE  clamshell  dredge  "Finn  MacCool,"  the  dredge  illustrated 
in  Fig.  55,  was  employed  on  the  extension  of  the  Buffalo  breakwater, 
and  was  operated  very  successfully  under  adverse  conditions. 
The  great  depth  of  water,  the  nature  of  the  material  and  the  large 


FIG.  55. — Dredge  "Finn  MacCool." 

amount  of  excavation  indicated  that  a  large  clamshell  dredge 
would  be  the  machine  best  adapted  for  the  work.  It  was,  therefore, 
decided  to  employ  a  clamshell  dredge,  and  the  contract  for  such  a 
machine  was  awarded  to  the  Osgood  Dredge  Co.  of  Albany,  N.  Y., 
by  Hughes  Bros.  &  Bangs,  the  contractors  for  the  breakwater. 
The  capacity  of  the  bucket  was  fixed  at  10  cu.yds.,  and  the  hull 
and  machinery  were  designed  with  this  capacity  as  a  basis. 

178 


DESCRIPTIONS   OF  CLAMSHELL  DREDGES  179 

The  hull  was  made  entirely  of  wood,  120  ft.  long,  40  ft.  beam,  and 
12  ft.  6  in.  deep.  The  length  given  does  not  include  a  moulded 
bow  and  stern  of  falsework,  which  were  added  to  make  the  dredge 
tow  easier,  and  which  increased  the  total  length  to  160  ft.  The 
A  frame  was  50  ft.  high  above  deck  and  the  boom  65  ft.  long.  There 
was  a  single  spud  at  each  end  of  the  hull,  but  these  spuds  instead 
of  extending  to  the  bottom,  acted  simply  as  attachments  for  the 
anchor  ropes  by  which  the  machine  was  really  held  in  position. 
The  usual  manner  of  anchoring  dredges  working  in  water  too  deep 
for  spuds  is  to  run  the  anchor  line  from  the  level  of  the  deck.  With 
a  beam  wind  and  heavy  sea  several  anchors  are  usually  required 
to  hold  the  dredge  in  place,  and  these  interfere  seriously  with  the 
free  handling  of  scows  and  tugs  alongside.  It  was  therefore  desired 
to  remedy  this  fault  in  constructing  the  present  machine. 

The  dredge  was  provided  on  each  side  with  a  spud,  3  ft. 
square,  which  extended  25  or  30  ft.  below  water.  At  the  bottom 
of  each  spud  there  were  three  sheaves,  two  fixed  across  the  spud 
and  one  fore  and  aft.  On  the  deck,  close  to  the  spud,  were  located 
three  other  sheaves.  The  anchor  lines  passed  from  the  drums  over 
the  sheaves  on  deck,  down  along  the  sides  of  the  spuds,  through 
guides  cut  in  the  spud  wells,  and  under  the  sheaves  in  the  bottom 
of  the  spud  out  to  the  anchors,  some  300  ft.  away.  This  arrange- 
ment held  the  dredge  with  anchors  in  six  different  directions,  the 
line  of  which  were  25  ft.  under  water,  giving  free  access  to  scows 
and  the  largest  tugs  to  approach  the  dredge  from  all  directions. 
In  actual  operation  the  center  bow  anchor  was  not  used,  as  it  wa's 
not  required,  and  its  removal  did  not  interfere  with  the  free  operation 
of  the  bucket.  The  remaining  five  anchors  have  proved  their  ability 
to  hold  the  dredge  on  the  line  of  the  work  with  a  strong  beam 
wind  and  heavy  sea.  The  dredge  moved  backward  along  the  line 
of  the  cut,  the  movement  being  accomplished  by  hauling  in  on  the 
center  stern  anchor  line.  A  patent  for  this  form  of  anchor  attach- 
ment was  secured  by  the  Osgood  Dredge  Co. 

Turning  now  to  the  operating  machinery,  the  main  engine, 
placed  amidship,  operated  the  dredge  bucket.  This  was  an  18  X 
24-in.  double-cylinder  engine,  with  Stephenson  reversing  gear,  and 
was  compound  geared  to  two  60-in.  drums,  with  gear  faces 
12  ft.  in  diameter  and  double  frictions  of  the  V  type,  the  male  V 
was  of  iron  and  the  female  lined  with  lignum  vitse.  The  male 
V  was  hollow,  and  to  keep  the  friction  faces  cool,  water  was 


180 


A  TREATISE   ON  DREDGES   AND   DREDGING 


circulated  through  them.  The  frictions  were  set  up  by  steam 
compressors,  so  arranged  as  to  apply  pressure  graduated  at  the 
will  of  the  engineer.  From  the  drums  four  1^-in.  37-wire  strand 
plow-steel  cables  ran  to  the  clamshell.  This  clamshell  bucket 
was  itself  of  rather  novel  construction,  as  shown  by  Fig.  56.  The 
bucket  was  of  10  cu.yds.  capacity,  and  when  empty  weighed  over 
30,000  Ibs.,  and  as  the  great  depth  of  water  precluded  the  use  of 
poles,  some  special  precautions  were  taken  to  prevent  it  from  twisting 


FIG.  56.— 10-cu.yd.  Clamshell  Bucket  of  the  Dredge  "Finn  MacCool." 

the  cables  together.  The  method  adopted,  as  seen  from  Fig.  56, 
was  to  employ  two  sheaves,  one  placed  on  each  side  of  the  bucket, 
and  to  operate  the  bucket  by  two  opening  and  two  closing  cables. 
As  these  four  cables  ran  over  four  sheaves  on  the  boom,  and  the 
cables  were  made  in  pairs,  with  right-  and  left-hand  lay,  there  was 
no  tendency  of  the  bucket  to  twist. 

The  secondary  engines  were  two  in  number,  each  being  a  double- 
cylinder  engine,  and  one  being  placed  aft  and  the  other  forward 
of  the  main  engine.  The  forward  engine  was  10x12  in.  and  drove 
three  friction  drums  for  handling  the  forward  anchor  lines  and 


DESCRIPTIONS  OF  CLAMSHELL  DREDGES  181 

six  upright  capstans  on  deck  for  handling  lines  and  scows.  The 
stern  engine  had  8x10  in.  cylinders  and  drove  the  three  friction 
drums  for  the  stern  anchors  and  two  capstans  on  deck.  Each  cap- 
stan was  fitted  with  independent  friction,  brake  and  rackets. 

Steam  was  supplied  to  all  three  engines  by  two  Roberts  water 
tube  boilers.  Each  boiler  had  46  sq.ft.  of  grate  surface  and  1200 
sq.ft.  of  heating  surface  and  was  built  for  250  Ibs.  steam  pressure, 
although  they  were  run  at  125  Ibs.  pressure.  All  the  engines  were 
piped  to  a  Wheeler  admiralty  condenser  and  also  to  a  free  exhaust 
pipe,  so  that  they  could  be  run  either  condensing  or  non-condensing. 

The  coal  consumption  was  estimated  from  four  to  five  tons  per 
day.  The  machine  was  operated  by  a  crew  of  ten  men.  In  regard 
to  the  efficiency  of  the  machine  it  worked  one  bucket  a  minute  in 
65  ft.  of  water.  Its  average  work  was  the  loading  of  ten  or  eleven 
scows  per  day,  the  capacity  of  each  scow  being  about  400  cu.yds. 
The  dredge  often  loaded  scows  in  30  and  40  minutes,  and  in  soft 
clay  repeatedly  loaded  a  pocket  containing  60  cu.yds.  with  four 
buckets  in  4  minutes  in  60  to  70  ft.  of  water. 

The  dredge  has  worked  very  satisfactorily,  working  quickly, 
easily  and  smoothly,  with  plenty  of  power  and  abundance  of  strength 
in  all  its  parts  and  with  great  steadiness. 

The  Clamshell  dredge  "  Champion " — a  new  departure,  namely 
the  opening  and  closing  of  a  clamshell  bucket  by  means  of  com- 
pressed air,  was  designed  by  Mr.  W.  H.  Arnold  and  used  in  the  dredge 
lt  Champion"  of  the  W.  H.  Beard  Dredging  Co.  of  New  York.  It  was 
described  in  the  Engineering  News,  May  2,  1901,  from  which  the 
following  condensed  description  was  taken: 

The  pneumatic  clamshell  dredge  bucket  is  an  innovation 
which  promises  to  have  a  wide  field  of  usefulness.  As  engineers 
familiar  with  this  type  of  dredging  apparatus  know,  the  ordinary 
chain-closed  clamshell  has  serious  defects.  The  bucket  can  be 
closed  only  after  it  has  come  to  rest  on  the  bottom,  and  the  pull  of  the 
closing  chains  reduces  the  effective  digging  weight  of  the  buckets 
owing  to  their  lifting  action.  To  avoid  these  objections  several 
attempts  have  been  made  to  devise  buckets  closing  by  the  action 
of  liquid  pressure  in  a  cylinder,  but  so  far  none  of  these  devices 
has  gained  much  favor.  The  bucket  illustrated  here  is  one  of  the 
latest  of  the  devices  and  has  given  very  good  results.  In  it  the 
opening  and  closing  of  the  bucket  is  performed  by  air  pressure 
operating  through  a  cylinder  and  piston,  the  action  being  wholly 


182 


A   TREATISE  ON  DREDGES   AND   DREDGING 


independent    of  the  hoisting  chains   and  of  the    position    of    the 
bucket. 

The  construction  of  the  bucket  is  seen  from  the  sectional  draw- 
ing, Fig.  57.    The  central  part  of  the  bucket  is  the  frame  A,  which 

terminates  at  the  top  in  a  fork  B,  and 
at  the  bottom  in  a  cylinder  C;  be- 
tween the  arms  of  the  fork  is  pivoted 
a  compensating  bar  D,  to  the  ends 
of  which  are  attached  the  hoisting 
chains,  and  at  the  bottom  of  the 
cylinder  there  is  a  wedge-shaped 
cylinder-head  guard  E.  The  com- 
pensating bar  serves  to  keep  the 
bucket  vertical  in  descending,  while 
the  cylinder-head  guard  serves  as  a 
means  for  anchoring  the  bucket  or 
for  holding  it  while  filling  in  a  fixed 
position  in  the  material  to  be  re- 
moved. The  shells  F  F  of  the 
bucket  are  hinged  to  ;the  frame  by 
four  bucket  arms  G,  and  are  also 
hinged  to  the  crosshead  T  by  the 
triangular  connecting  links  H.  This 
crosshead  is  keyed  to  the  top  of  the 
piston  rod  and  slides  between  interior 
guides  on  the  two  members  of  the 
frame. 

In  operation,  the  jaws  or  shells 
of  the  bucket  are  both  opened  and 
closed  by  the  positive  action  of  the 

air  pressure  upon  the  bottom  or  top  of  the  piston.  The  air  is  con- 
veyed to  the  cylinder  from  the  receiver  on  the  dredge  through  a 
double-barreled  or  Siamese  hose  arranged  as  described  later.  It 
will  be  observed  from  the  drawing  that  the  opening  and  closing 
mechanism  is  wholly  independent  of  the  devices  by  which  the 
bucket  is  hoisted  and  lowered,  so  that  it  may  be  closed  at  any 
point  in  its  vertical  travel.  Furthermore,  it  will  be  seen  that  when 
the  bucket  rests  on  the  bottom  its  whole  weight  is  effective  for 
digging,  the  hoisting  chains  remaining  slack  until  the  jaws  are 
closed. 


FIG.    57.— Sectional    View   of    the 
Clamshell  Bucket  "Arnold." 


DESCRIPTIONS  OF  CLAMSHELL   DREDGES 


183 


The  dredge  (Fig.  58)  is  of  the  ordinary  flat-deck  type  and  in 
appearance  is  similar  to  any  other  clamshell  dredge,  the  only  differ- 
ence being  a  hose  reel  on  the  boom  and  the  unusual  installation  of 
air  compressor  and  receiver. 

The  problem  of  handling  the  hose  during  operation  was  a  some- 
what critical  one.  It  was  necessary,  of  course,  that  the  hose  should 
freely  follow  the  bucket  in  its  descent  and  as  freely  and  quickly  be 
gotten  out  of  the  way  in  the  ascent  of  the  bucket.  It  was  highly 
desirable  also  that  these  operations  should  be  automatic.  The 


FIG.  58.— Dredge  "Champion." 

solution  of  the  problem  was  exceedingly  simple.  A  vertical  hose  reel 
with  a  hollow  shaft  or  axle  is  carried  on  bearings  on  the  top  member 
of  the  boom.  From  the  receiver  two  lines  of  iron  pipe  pass  up 
the  boom  and  terminate  in  the  ends  of  the  hollow  shaft.  The  double 
hose  has  connections  tapped  into  the  shaft  to  admit  the  air  to  it. 
In  operation  the  hose  is  unwound  from  the  reel  by  direct  pull  when 
the  dipper  is  descending.  This  action,  of  course,  rotates  the  reel 
and  this  rotation  winds  up  a  cable  attached  to  a  counterweight 
which  slides  up  and  down  the  boom  on  an  interior  track.  When 
the  bucket  begins  to  ascend  and  releases  the  tension  on  the  hose, 
the  counterweight  acts  by  gravity  to  unwind  the  counterweight 


184  A  TREATISE  ON  DREDGES   AND   DREDGING 

cord  which  rotates  the  reel  in  the  reverse  direction  and  winds  the 
hose  onto  it  as  fast  as  it  comes  out  of  the  water.  Both  the  unwind- 
ing and  rewinding  actions  are  wholly  automatic  and  require  no 
particular  care  on  the  part  of  the  operator. 

On  the  dredge  "  Champion  "  a  double  or  Siamese  hose  was  used, 
one  barrel  of  which  supplied  air  to  the  bottom  of  the  piston  and  the 
other  to  the  top  of  the  piston.  A  pressure  of  100  Ibs.  per  sq.in.  was 
used.  The  admission  of  the  air  to  the  cylinder  and  its  exhaust 
were  controlled  by  a  three-way  cock  on  each  of  the  two  lines  of 
pipe  leading  to  the  hose,  these  cocks  being  placed  in  the  operator's 
cabin  close  to  the  hand  of  the  dredge  operator. 

The  main  dimensions  of  the  bucket  used  on  the  dredge  ''Cham- 
pion" were:"  Capacity,  3  cu.yds.;  diameter  of  cylinder,  16 in.;  area 
of  piston,  200  sq.in. ;  length  of  stroke,  4  ft. ;  working  pressure  of  air, 
100  Ibs.  per  sq.in. ;  total  pressure  on  piston,  20,000  Ibs. ;  total  weight 
of  reciprocating  parts,  9000  Ibs.;  total  closing  force  on  material, 
29,000  Ibs.;  actual  weight  of  bucket,  24,000  Ibs.  This  bucket  was 
designed  for  hard  digging.  For  soft  material  a  larger  bucket  is 
employed  and  for  handling  blasted  rock  the  bucket  shell  is  replaced 
by  grapples. 

The  advantages  claimed  for  this  form  of  clamshell  over  chain- 
closing  buckets  are:  Closing  and  opening  independent  of  use  of 
frictions;  bucket  can  be  lowered  into  scow  well  and  dumped  on  the 
doors  without  dropping  the  load;  a  gain  of  about  10  ft.  in  width 
of  cut  is  made  owing  to  the  fact  that  the  chain-closed  bucket  will 
fall  off  in  opening.  The  entire  weight  of  the  bucket  is  on  the  bottom 
while  closing,  and  finally  the  ability  to  close  the  bucket  at  a  given 
depth  enables  the  dressing  off  of  the  bottom  of  the  cut  at  the  required 
depth  without  excess  excavation. 


CHAPTER  XXIII 

TRANSPORTATION    OF   THE  DEBRIS.     CONVEYORS,  BARGES, 

ELEVATORS 

THE  dredged  materials  are  disposed  of  in  different  ways.  They 
can  be  used  for  filling  lowlands,  for  regulating  the  shores  of  the 
river  or  canal  alongside  the  improvement,  and  when  they  cannot 
be  utilized  in  any  other  way,  are  dumped  into  deep  waters.  In  any 
case  the  debris  must  be  transported  a  certain  distance,  which 
varies  according  to  the  local  conditions.  There  are  different  means 
of  transporting  the  dredged  materials,  depending  upon  the  machine 
employed  and  the  method  of  disposing  of  the  debris.  Thus,  for 
instance,  when  the  machine  used  is  not  of  the  hopper  type,  or  when 
the  dredge  itself  does  not  transport  the  materials  removed  from  the 
bottom,  the  debris  is  conveyed  to  the  dumping  place  either  by 
conveyors,  pipes,  or  by  means  of  barges  or  scows. 

Belt  Conveyors.  In  the  description  of  the  low-tower  ladder 
dredge  used  in  the  improvement  of  the  Fox  River,  Wis.,  given  on  page 
86,  was  illustrated  the  method  of  conveying  the  debris  from  dredge 
to  land  by  means  of  a  belt  conveyor.  This  method,  which  was  used 
many  years  ago  in  connection  with  land  dredges  at  Tabernilla, 
Panama,  under  the  French  Administration,  has  been  very  recently 
introduced  in  this  country  for  the  transportation  of  the  debris 
removed  from  the  bottom  of  rivers  by  means  of  ladder  dredges. 
This  method  is  so  simple  that  the  description  of  the  one  given  will 
be  more  than  sufficient  to  explain  it. 

Pipe  Conveyors.  Another  manner  of  transporting  or  conveying 
the  debris  from  the  dredge  to  the  nearby  lands  is  by  means  of  pipe 
conveyors.  These  are  used  in  connection  with  the  high-tower  ladder 
dredges  and  with  the  hydraulic  and  pneumatic  dredges.  In  the 
former  case  the  debris  descends  through  the  pipe  by  gravity;  in 
the  latter  it  is  under  pressure  and  consequently  they  can  be  dis- 
charged at  a  point  higher  than  the  dredge  itself. 

The  following  description  of  a  pipe  conveyor  used  in  connection 

185 


186  A  TREATISE  ON  DREDGES  AND   DREDGING 

with  a  high  tower  dredge  in  the  excavation  of  Suez  Canal,  taken  from 
Spoon's  Engineering  Encyclopedia  will  serve  to  illustrate  this  method 
of  transporting  the  debris  from  the  dredge  to  land. 

At  Suez  the  ladder  dredges  were  provided  with  high  towers  and 
discharged  their  contents  into  an  extra  long  chute.  See  Fig.  59. 
The  length  of  the  chute  from  the  center  of  the  dredge  was  230  ft. 
with  an  elliptical  cross-section  2J  ft.  wide  and  5  ft.  high.  The 
height  of  the  upper  tumbler  of  the  ladder  was  48  ft.  above  the  water. 
Two  centrifugal  pumps  supplied  water  to  facilitate  the  discharge 
of  the  spoil.  To  support  the  chute  for  its  entire  length  a  latticed 
cantilever  beam  was  constructed  which  rested  both  on  the  dredge 
and  on  an  iron  pontoon  which  was  placed  about  one-third  of  its 
length  from  the  dredge.  Two  uprights  which  stiffened  the  chute 


FIG.  59. — Ladder  Dredge  with  Pipe  Conveyor. 

were  not  fixed  to  the  pontoon,  but  rested  on  beams  placed  longi- 
tudinally on  the  pontoon.  A  horizontal  hinge  coupled  the  chute  to 
the  dredge  and  allowed  its  inclination  to  be  altered.  To  permit 
changes  in  the  inclination  of  the  chute,  the  uprights  which  supported 
it  were  made  telescopic.  The  chute  was  lifted  by  two  small  hy- 
draulic presses  worked  by  hand. 

Observations  made  on  the  passing  of  difficult  materials  through 
chute  showed  the  following  results.  Only  fine  sands  were  excavated 
and  they  passed  easily  down  a  chute  inclined  1  in  20  or  25  if  mixed 
with  a  quantity  of  water  equal  to  about  one-half  their  own  bulk. 
When  the  chute  has  an  inclination  less  than  1  in  25  the  water  sepa- 
rates from  the  sand  which  is  thus  deposited  all  along  the  chutes  in 
layers  of  continually  increasing  thickness.  The  addition  of  a  larger 
quantity  of  water  does  not  seem  to  make  the  chute  more  effective, 
and  it  is  necessary  to  stir  the  sand  with  a  shovel.  When  the  sand 


TRANSPORTATION  OF  THE  DEBRIS  187 

i 

contains  shells,  they  are  deposited  in  the  chute.  The  shells  create 
around  them  deposits  of  sand  which  continually  increase  and  must 
be  removed  either  with  shovels,  or  by  increasing  the  inclination 
of  the  chute.  A  greater  volume  of  water  is  of  no  avail.  With 
various  degrees  of  fineness  of  the  sand  and  mud,  it  was  found  that 
different  inclination  of  the  chute  were  required. 

Mud  behaves  very  much  like  sand.  If  it  is  sufficiently  soft 
to  mix  with  water  it  will  pass  down  a  chute  set  with  very 
slight  inclination.  The  very  soft  mud  at  Suez,  such  as  that  from 
the  old  channels  previously  cut  through  the  clay  ground,  does  not 
require  the  addition  of  any  water  in  the  chute.  With  clay  it  is 
quite  different;  the  addition  of  water  washed  away  only  a  very 
small  quantity  of  the  material,  and  hardly  breaks  up  the  lumps. 
If  each  lump  of  clay  were  to  slide  perfectly  straight  down  the  chute, 
all  would  work  well;  however,  a  lump  winds  about  and  soon  stops, 
and  the  contents  of  the  next  bucket  drives  it  on  5  or  10  ft.,  and  this 
increases  the  trouble,  until  the  mass  gets  to  be  12  or  16  in.  in  thickness 
and  reaches  to  the  top  end  of  the  chute,  when  the  contents  of  the 
succeeding  buckets  seem  to  break  it  up,  and  the  mass  descends 
quietly  and  regularly  in  pieces  of  about  3  to  6  ft.  length.  The  chutes 
for  clay  are  inclined  from  1  in  12  to  1  in  16.  With  an  inclination 
of  1  in  20  the  work  is  more  regular.  When  the  clay  is  mixed 
with  sand  the  surface  acts  like  a  rasp,  because  the  water  washing 
away  the  clay  leaves  the  grains  of  sand,  and  their  grinding  and 
cutting  are  detrimental  to  the  chute. 

Experience  has  thus  shown  that  while  a  considerable  supply 
of  water  must  be  added  to  sand,  it  is  not  so  for  mud  or  clay,  to  which 
just  enough  water  must  be  added  to  moisten  the  mass.  Jets  of 
water  have  not  given  good  results;  they  merely  wash  down  the 
points  against  which  they  are  directed  and  do  not  break  up  the 
lumps.  In  dredges  with  chutes  230  ft.  length  an  endless  travel- 
ing chain  is  employed,  driven  by  the  engine  and  furnished  with 
a  series  of  scrapers  to  carry  the  clay  down  the  chute.  Generally 
the  greatest  difficulty  with  all  kinds  of  spoil  is  in  passing  through 
the  first  40  or  50  ft.  of  the  chute.  When  once  the  material  has  passed 
this  with  any  given  inclination,  it  continues  moving  on  down  the 
same  inclination  without  any  further  difficulty. 

Very  often  the  materials  removed  from  the  bottom  by  hydraulic 
dredges  are  used  to  fill  up  lowlands  near  by,  and  are  transported 
by  means  of  a  long  line  of  pipes.  The  pipes  used  are  of  different 


188  A  TREATISE  OX   DREDGES  AND   DREDGING 

shapes  and  sizes  to  satisfy  local  conditions,  but  generally  they 
consist  of  sections  of  pipes  bolted  together  and  supported  by  floats 
of  any  design.  The  various  sections  of  pipes  are  joined  together  in 
some  way  so  as  to  permit  the  whole  line  to  adjust  itself  to  tides, 
currents  and  other  circumstances. 

The  following  description,  taken  from  Engineering,  will  serve 
to  illustrate  the  method  of  conveying  the  materials  from  dredges 
to  land  by  means  of  a  pipe  line.  It  was  used  in  connection  with  the 
hydraulic  dredge  "  J.  Israel  Tarte"  designed  by  Mr.  W.  Robinson  for 
deepening  the  channel  through  Lake  St.  Peter  in  the  River  St. 
Lawrence. 

The  form  of  pipe  line  adopted  is  that  of  a  central  conduit  36 
in.  in  diameter,  carried  by  two  cylindrical  pontoons  or  air  chambers 
42  in.  diameter,  the  three  being  bound  together  by  truss-frames 
clamped  upon  them  as  shown  in  Fig.  60,  Cut  A.  In  this  way  no 
bolts  or  rivets  are  put  into  the  air  chambers,  and  they  may  be  readily 
taken  apart.  —r- 

The  pipes  were  made  up  in  100-ft.  sections,  and  four  sections 
of  50  ft.  were  made  with  the  idea  of  putting  them  in  that  part  of 
the  pipe  where  greater  flexibility  was  required.  It  was  found,  how- 
ever, that  these  5-ft.  pipes  did  not  stand  the  sea  as  well  as  the  100- 
ft.  sections  and  that,  moreover,  sufficient  flexibility  could  be  had 
without  them.  They  were  accordingly  joined  together  and  con- 
verted into  100-ft.  sections. 

The  joints  connecting  the  100-ft.  sections  were  at  first  made 
by  uniting  them  with  a  forged-steel  pin  connection  over  the  rubber 
sleeve,  thus  relieving  the  rubber  sleeve  of  all  strain  due  to  tension 
of  the  pipe  and  permitting  the  required  angular  movement.  These 
joints  were  not  strong  enough,  and  were  found  to  be  too  rigid  in 
wave-action  and  caused  heavy  strains  to  be  set  up,  which  broke 
some  of  the  joints.  They  were  temporarily  repaired  for  the  first 
season,  and  during  the  winter  1902-03  new  joints  of  special  con- 
struction were  devised  by  Mr.  Robinson  on  the  ball-and-socket  plan 
to  permit  of  universal  movement  to  a  moderate  degree,  and  also 
fitted  with  draw-bar  springs  to  allow  of  variations  in  length  due 
to  surging  and  pitching.  The  ball-and-socket  principle  was  embodied, 
not  in  the  pipe  itself,  but  in  a  strong  steel  frame  above  the  pipe,  which 
was  connected  by  rubber  sleeves  in  the  usual  manner.  This  has 
proved  entirely  successful,  and  the  practical  result  is  that  the  dredge 
is  capable  of  continuing  at  work  in  all  but  the  heaviest  weather. 


TRANSPORTATION  OF  THE  DEBRIS 

• 


189 


The  general  construction  of  the  pipe  line  and  joints  are  illustrated  in 
Fig.  60,  Cuts  B,  C,  and  D.  The  ball  end  of  the  joint  is  solidly  riveted 
to  the  frames  on  the  pipe,  while  the  socket  is  fitted  to  slide  in  a 
casing  or  frame,  and  its  movement  is  resisted  by  springs  as  shown. 
These  springs  are  two  in  number  and  are  heavy  car  springs.  They 


B 


FIG.  60.— Pipe  Line  Conveyor  of  the  Dredge  "  J.  Israel  Tarte." 

are  6J  in.  in  diameter  and  8  in.  long  arid  made  of  round  steel  1J  in. 
in  diameter.  The  springs  are  carried  between  spring-plates,  resting 
against  stops  in  such  a  way  that  the  springs  are  compressed  for 
either  thrust  or  pull  of  the  draw-bar,  and  the  whole  arrangement 
is  built  of  steel  in  the  very  strongest  manner,  and  each  joint  is 
strong  enough  vertically  to  carry  half  the  entire  weight  of  the  pon- 
toon upon  it.  In  other  words,  should  the  entire  buoyancy  be  removed 


190  A  TREATISE  ON  DREDGES   AND   DREDGING 

from  one  pontoon  for  50  ft.  of  its  length  by  the  trough  of  a  wave, 
its  weight  could  be  rested  upon  the  adjoining  pontoon  with  safety. 
No  anchorage  is  used  at  any  intermediate  point  of  the  pipe. 
It  is  attached  at  one  end  to  the  dredge  and  at  the  other  by  a  short 
cable  to  scow,  the  entire  2000  ft.  being  free  to  drift  as  it  pleases. 
The  scow  is  fitted  with  a  steam  winch,  by  which  its  own  anchorage 
is  controlled.  It  has  two  anchors  with  wire  cables  1J  in.  diameter 
and  2000  ft.  long.  These  can  be  hauled  in  and  paid  out  as  required 
and  this  movement  serves  both  to  distribute  the  material,  to  avoid 
piling  up  above  the  surface  of  the  water,  and  also  to  regulate  the 
tension  of  the  pipe  when  the  dredge  is  making  a  very  wide  cut. 
In  places,  when  the  cut  is  750  ft.  wide  the  pipe  tightens  up  to  almost 
a  straight  line  when  the  dredge  is  at  the  far  side.  The  scow  anchor- 
age permits  considerable  freedom  of  movement,  and,  when  neces- 
sary, the  operator  on  the  scow  pays  out  on  his  anchorage  to  relieve 
and  permit  the  dredge  to  make  the  cut. 


FIG.  61.— Open-hold  Barge. 

Scows.  The  scows  used  for  the  transportation  of  the  dredged 
materials  are  of  different  types,  which  for  sake  of  classification  can 
be  grouped  in  open-hold  scows,  deck  scows  or  floats,  and  dumping 
scows.  Each  group  can  be  subdivided  again. 

Open-hold  Barges.  The  ordinary  barges  or  lighters  used  for  the 
transportation  of  various  materials  along  canals  and  rivers  can  be 
also  employed  for  carrying  away  the  dredged  debris.  As  a  general 
rule  these  vessels  are  not  the  most  convenient  and  economical, 
yet  there  are  eases  in  which  even  these  barges  can  be  employed  with 
advantage.  In  the  open-hold  barges  the  material  is  deposited 
directly  on  the  bottom  of  the  boat,  the  floor  being  formed  by  planks 
placed  longitudinally  and  resting  on  the  keelsons — Fig.  61.  The 
empty  space  included  between  the  said  platform  and  the  sides  of  the 
boat  determines  the  capacity  of  the  vessel,  which  capacity  varies  con- 
siderably. This  type  of  barge  is  very  seldom  used  for  the  transporta- 
tion of  the  dredged  materials,  owing  to  the  difficulty  of  removing  the 
debris  from  the  bottom  of  the  scow.  It  is  only  used  in  the  improve- 


TRANSPORTATION  OF  THE  DEBRIS  191 

• 

merits  of  rivers  and  canals  in  connection  with  the  ladder,  dipper 
and  grab  dredges,  when  the  material  must  be  transported  to  a  certain 
distance  and  raised  again  by  some  machine.  In  such  a  case  the 
sides  of  the  boat  prevent  the  scattering  of  the  material  under  the 
stirring  action  of  the  lifting  machine;  but  the  platform  forming 
the  bottom  of  the  boat  is  subjected  to  hard  usage  and  easily  wears 
out. 

In  regard  to  the  shape,  the  open-hold  barges  are  built  with 
flat  bottoms  to  insure  steadiness  and  light  draft,  thus,  too,  making 
their  construction  cheap.  In  barges  of  large  dimensions  the  hori- 
zontal beams  or  keelson  are  subjected  to  unusual  stress,  and  it  is 
worthy  of  note  that  in  the  barges  used  for  the  transportation  of 
the  rock  excavated  from  the  site  of  the  new  Pennsylvania  Station 
in  New  York  city,  all  the  beams  of  the  floor  of  the  barges,  under 
the  double  action  of  the  pressure  of  waves  below  and  the  material 
above,  broke  along  the  line  of  neutral  axis.  They  showed  a  seam 
as  long  as  the  beam  itself,  while  the  beam  remained  unaffected 
on  the  upper  and  lower  part,  in  apparent  contradiction  to  the 
well-known  theory  of  tension  and  compression  in  the  two  parts 
of  the  beams. 

Deck  Scows  or  Pontoons.  These  are  used  for  the  transportation 
of  the  dredged  materials  on  rivers  and  canals,  when  the  materials 
deposited  on  deck  of  the  barges  have  to  be  raised  to  be  sent  to  the 
dumping  place.  This  type  of  barge  is  subdivided  again  into  deck- 
scows  proper,  railroad  floats  and  deck-scows  with  open  boxes. 
The  deck-scows  are  always  built  of  rectangular  design  with  flat 
bottom  to  insure  light  draft,  and  they  are  made  of  soft  wood  both 
in  the  frame  and  planking. 

The  deck-scows  proper  are  used  for  the  transportation  of  the 
dredged  materials  when  they  are  deposited  in  skips  which  are  lifted 
by  derricks  or  cranes  and  unloaded  again,  either  directly  onto  the 
ground  or  into  cars  to  be  conveyed  to  distant  points.  But  this 
method  of  transporting  dredged  materials  is  not  very  common, 
and  is  used  only  under  unusual  conditions,  as  for  instance  on  the 
Fonage  Canal  along  the  Rhone  River  in  France. 

When  the  dredged  materials  are  used  for  filling  lands  some 
distance  from  the  shore  instead  of  using  skips  it  is  more  economical 
to  deposit  the  debris  directly  into  railroad  cars  located  on  the  deck 
of  a  scow.  For  such  purposes  the  deck  of  the  pontoon  is  provided 
with  several  parallel  tracks  upon  which  are  placed  the  cars.  After 


192  A  TREATISE  ON  DREDGES   AND   DREDGING 

all  the  cars  have  been  loaded,  the  float  is  towed  to  some  distant 
point  and  moored  to  a  convenient  place  where  there  are  tracks 
in  continuation  and  -flush  with  those  located  on  the  float.  At 
the  landing  pier  a  locomotive  pulls  out  one  row  of  cars  at  a  time 
and  after  the  train  is  formed  it  is  sent  to  the  dumping  place,  while 
empty  cars  are  replaced  on  the  float  and  towed  back  to  the  dredge 
to  be  filled  with  dredged  material.  This  method  of  transportation 
can  be  used  onty  in  connection  with  the  clipper  and  clamshell 
dredges,  and  although  it  can  be  found  convenient  in  some  cases 
it  has  the  great  disadvantage  that  it  is  difficult  to  load  the  cars, 
part  of  the  material  falling  between  the  tracks  and  must  be 
removed  by  hand. 

Deck  Barges  with  Cargo  Box.  The  dredged  materials  can  be 
transported  also  on  deck  barges  with  cargo  boxes,  when  the  barges 
will  be  unloaded  by  means  of  clamshell  or  orange-peel  buckets. 
This  method  of  transportation  is  commonly  used  in  connection 
with  gravel  and  sand  dredging  for  commercial  purposes.  The  cargo 
box  is  formed  by  fitting  side  boards  about  3  ft.  high  and  arranging 
hopper  ends,  inclosing  nearly  all  the  deck  area,  leaving  but  a  small 
space  at  each  end  for  handling  lines.  The  barges  used  for  carrying 
sand  on  the  Mississippi  River  are  subjected  to  severe  strains,  and  so 
several  steel-deck  barges  have  been  placed  in  service  by  one  of  the 
largest  sand  companies  on  the  river.  These  barges  are  130  ft.  long, 
30  ft.  wide  and  7^  ft.  deep.  A  complete  steel  deck  is  fitted,  and  on 
this  a  wood  box  is  arranged,  by  fitting  timber  side  boards  3  ft.  high. 
The  deck  beams  are  framed  longitudinally  so  as  to  better  care  for 
the  impact  of  the  grab  bucket,  which  is  used  with  its  cutting  edges 
across  the  barge. 

Dumping  Scows.  The  transportation  of  the  debris  from  the 
dredging  point  to  the  dump  in  high  seas,  when  not  made  by  the 
dredge  itself,  is  done  by  means  of  dumping  scows.  These  are  usually 
composed  of  an  ordinary  deck  scow  with  one  large  or  several  small 
holds  having  the  floors  formed  by  the  trap  doors.  The  debris  is 
deposited  into  these  compartments  and  when  the  doors  are  opened 
the  contents  fall  out  by  gravity.  It  is  more  convenient  to  have 
the  scow  divided  into  many  separated  compartments  instead  of 
one  large  one.  Such  an  arrangement  will  greatly  facilitate  the 
operation  and  prevent  the  great  weight  of  the  load  from  straining 
the  mechanism  controlling  the  doors. 

Dumping  scows  are  constructed  of  different  shapes  and  sizes. 


TRANSPORTATION  OF  THE  DEBRIS  193 

American  manufacturers  are  building  dumping  scows  of  very  large 
dimensions,  not  less  than  200  ft.  long  and  40  ft.  beam,  divided 
into  four  or  five  compartments,  each  shaped  as  an  inverted  frustum 
of  a  pyramid  with  the  floor  formed  by  a  trap  door.  This  door  is 
hinged  at  one  side  and  at  the  opposite  side  is  controlled  by  chains 
wound  around  a  shaft,  located  on  deck  and  parallel  to  the  longi- 
tudinal axis  of  the  scow.  This  shaft,  through  a  system  of  cogwheels, 
is  revolved  either  by  a  steam  winch  or  by  a  capstan  worked  by  hand 
power.  When  the  dumping  place  has  been  reached,  the  brakes 
that  keep  the  shaft  in  position  are  removed,  the  weight  of  the 
materials  pressing  on  the  floor  of  the  compartments  opening  the 
doors  and  thus  dumping  the  load.  It  is  in  closing  the  doors  that 
either  the  steam  winch  or  the  hand  capstan  comes  into  play. 

The  European  dumping  scows  as  a  rule  are  smaller  than  the 
American,  but  are  built  of  a  large  variety  of  designs.  They  are 
generally 'provided  with  a  central  partition  which  divides  the  hold 
into  two  separate  longitudinal  compartments.  The  shaft  for  the 
opening  and  closing  of  the  trap  door  is  located  on  top  of  the  central 
partition.  The  advantage  of  such  construction  is  that  the  doors 
are  smaller,  consequently  less  strain  is  placed  on  the  brakes  which 
keep  the  doors  fastened.  Even  these  two  longitudinal  hoppers 
are  usually  subdivided  into  others,  every  one  of  them  being  in  the 
shape  of  an  inverted  frustum  of  a  pyramid.  But  the  shape  of 
these  hoppers  varies  with  the  material  to  be  transported ;  thus,  for 
clay,  the  sides  of  the  hopper  should  be  kept  as  vertical  as  possible 
U>  prevent  the  material  sticking  and  clogging  the  doors,  as  they 
would  if  the  sides  were  inclined.  For  the  transportation  of  fine 
sand  and  mud  the  bottom  of  the  hoppers,  instead  of  being  provided 
with  doors,  have  conic  valves  fitting  circular  openings.  By  simply 
raising  these  valves  the  materials  will  immediately  escape  through 
the  openings. 

Fig.  62,  A  and  B,  show  the  cross-sections  of  two  different  types 
of  dumping  scows  employed  on  the  construction  of  Suez  Canal. 
These  scows  were  constructed  with  flat  bottom  in  order  to  have 
light  draft;  but  when  the  material  has  to  be  dumped  in  deep 
water  in  the  high  sea  the  scow  is  constructed  with  a  hull  similar 
to  any  sea-going  boat.  Fig.  63,  shows  the  cross-section  of  a  dump- 
ing scow  constructed  to  convey  and  discharge  dredged  materials  into 
shallow  waters.  In  such  a  scow  should  the  trap  doors  form  the 
floor  as  usual,  and  open  downward,  they  would  reach  the  bottom 


194 


A  TREATISE  ON  DREDGES   AND   DREDGING 


and  could  not  be  entirely  opened,  thus  preventing  the  discharge 
of  the  load.  To  avoid  this  the  doors  are  placed  on  both  sides  of 
the  scow  and  the  hoppers  are  inclined  outwardly  to  facilitate  the 
descent  of  the  materials,  once  the  doors  are  open. 

Dumping  scows  are  tied  one  behind  another  by  long  lines,  form- 
ing a  tow  composed  of  3,  4  or  5,  and  towed  to  the  dumping  place 


FIG.  62. — Dumping  Scows  used  at  Suez. 

by  a  tugboat.  But  this  method  of  hauling  is  not  always  possible, 
especially  when  the  sea  is  rough,  as  the  rolling  of  the  various  scows 
will  disarrange  the  lines,  causing  loss  of  time  and  often  injuring  the 
scows.  To  avoid  this,  dumping  scows  are  built  in  the  shape  of 
any  ordinary  sea-going  vessel  and  are  self-propelling.  In  the  con- 
struction of  the  Suez  Canal,  in  transporting  material  from  the  Cana? 


FIG.  63. — Dumping  Scow  for  Shallow  Water. 

prism  to  the  dump  at  the  Bitter  Lakes,  some  self-propelling  dumping 
scows  were  used.  They  were  provided  with  bottom  doors,  were 
108  ft.  long,  with  23  ft.  beam,  carrying  160  cu.yds.  of  spoil  and 
drawing  5  ft.  of  water.  They  were  fitted  with  twin  screws  and  a 
pair  of  cylinders  placed  end  to  end.  The  engines  worked  at  high 
pressure  without  a  condenser,  with  a  tubular  boiler  at  120  Ibs. 
pressure,  using  only  fresh  water.  Whether  loaded  or  light  they 


TRANSPORTATION  OF  THE   DEBRIS 


195 


made  a  speed  of  3  to  3J  miles  per  hour,  and  although  built 
especially  for  the  lakes  they  could  be  sent  to  sea.  Their  construc- 
tion was  simple  and  economical  and  it  was  found  that  the  pressure 
engines  were  preferable  to  those  of  medium  pressure,  as  being 
simpler,  lighter  and  easier  to  keep  in  working  order  and  conse- 
quently could  be  relied  upon  for  continuous  work. 

To-day,  instead  of  simple  dumping  scows,  are  built  regular  sea- 
going hopper  steamers  with  a  capacity  of  about  1000  tons,  and  able 


FIG.  64. — Sea-going  Steam  Hopper. 

to  navigate  in  any  kind  of  weather.  Fig.  64  shows  one  of  these 
hopper  steamers  as  built  by  the  firm  A.  F.  Smulders  of  Rotterdam, 
for  the  Russian  Government. 

Dumping  scows  are  far  more  economical  than  the  hopper  steamers 
both  in  the  original  cost  of  construction  and  in  the  running  expenses. 
For  this  reason  contractors  in  the  equipment  of  their  plants  will 
always  prefer  dumping  scows  to  hopper  steamers.  The  latter, 
however,  are  more  reliable  for  continuous  work  and  supply  a  rapid 
and  uninterrupted  means  of  transportation  for  the  debris  of  the 
dredges  which  work  day  and  night  on  river  and  harbor  improve- 


196 


A   TREATISE  ON   DREDGES   AND   DREDGING 


ments.  These  hopper  steamers  being  very  expensive,  only  govern- 
ments and  public  corporations  can  afford  to  invest  an  enormous 
capital  for  the  sole  purpose  of  obtaining  a  better  means  of  trans- 
portation. On  account  of  the  almost  prohibitive  cost  of  the  steam 
hoppers,  manufacturers  have  devised  schemes  to  extend  their  utility. 
The  propelling  machines  have  been  increased  in  power  so  that  the 
steamer  could  be  used  as  a  tugboat;  and  in  many  cases  with  good 
weather  prevailing  have  been  used,  even  with  a  full  cargo,  to  tow  a 
line  of  dumping  scows.  Steam  hoppers  have  been  also  supplied  with 
fire-extinguishing  pumps  so  as  to  be  utilized  as  a  fireboat.  In  such 
cases  the  steam  hopper  performs  a  double  duty.  Steam  hoppers  have 


FIG.  65. — Dumping  Scow  with  Sliding  Platform. 

also  been  supplied  with  a  centrifugal  pump  and  a  suction  tube,  and 
thus  have  been  converted  into  a  sea-going  hopper  hydraulic  dredge  of 
small  capacity,  convenient  for  cleaning  the  quays  and  piers  around 
the  harbor.  Finally  the  steam  hoppers  have  been  used  for  life- 
saving  purposes  and  for  helping  vessels  that  are  in  distress.  Thus 
the  steam  hoppers  "San  D'emetrio"  and  "San  Caledonio"  built  by 
H.  Satre  &  Co.  and  used  in  the  improvements  of  the  harbor  of 
Santander,  Spain,  on  many  occasions  during  the  great  storms  pre- 
vailing in  that  locality  have  put  to  sea  and  helped  numerous  fishing 
smacks  and  steamboats. 

Another  type  of  dumping  scow  built  on  an  entirely  different 
principle  was  used  for  dumping  rocks  in  the  dyke  construction 
at  Newburyport,  Mass. 


TRANSPORTATION   OF  THE   DEBRIS 


197 


The  scow  (see  Fig.  65)  is  about  62}  ft.  long  and  22  ft.  wide; 
on  this  is  placed  a  platform  32  ft.  long  and  22  ft.  wide,  which  is 
arranged  to  slide  on  8  roller  ways  inclined  at  an  angle  of  1  in  28, 
transverse  to  the  axis  of  the  boat.  Between  these  ways  there  are 
three  struts  or  braces,  one  in  the  middle  and  the  others  near  the 
ends  of  the  platform.  The  lower  ends  of  these  braces  turn  on  a  vertical 
bolt  fixed  to  the  deck  of  the  boat  and  the  upper  ends  abut  against 
strong  blocks  fixed  to  the  platform.  These  three  braces  are  tied 
together  by  a  rod  attached  to  a  lever  which  by  a  simple  movement 


FIG.  66.— Sidewheel  Tugboat. 

releases  the  braces  from  their  blocks  and  leaves  the  platform  rest- 
ing free  on  the  rollers.  Wooden  guides  keep  the  platform  to  its 
track. 

The  dumping  operation  is  as  follows:  As  soon  as  the  braces  are 
released  the  platform  glides  outward  on  the  inclined  track  by  reason 
of  its  load.  After  moving  about  3}  ft.  it  is  checked  by  bringing 
in  contact  the  blocks  fastened  one  to  the  platform  and  the  other 
to  the  deck  of  the  boat.  Under  the  change  in  the  center  of  gravity 
the  boat  assumes  the  position  shown  in  Fig.  65  B  until  the  deck 
load  is  discharged,  an  operation  consuming  about  10  seconds. 


198 


A  TREATISE  ON  DREDGES  AND   DREDGING 


As  soon  as  the  empty  boat  rights  itself  again,  the  workmen  run 
the  platform  back  into  position  and  secure  it  there  by  the  braces. 

The  tugboats  used  for  towing  scows  are  too  well  known  to  be 
discussed.  They  are  generally  screw  propellers  or  sidewheel 
steamers  of  great  efficiency  and  light  draft.  Fig.  66  shows  a 
sidewheel  steamer  used  for  towing  purposes  in  shallow  rivers. 
Fig.  67  shows  a  screw  propeller  steamer  built  by  the  F.  Smulder  Co. 
of  Rotterdam  for  towing  scows  in  deep  waters. 

With  the  exception  of  the  dumping  scows  the  dredged  materials 
transported  by  means  of  any  other  scow  to  reach  its  final  desti- 


* 


FIG.  67. — Screw-propelled  Tug  Boat. 


nation  must  be  raised  up.  This  is  effected  by  means  of  different 
machines,  namely,  the  bucket  elevators,  the  derricks  and  grab 
buckets. 

The  bucket  elevator  consists  as  a  rule  of  a  land  dredge,  of  the 
down-digging  type  mounted  either  on  a  fixed  scaffold  or  on  the 
platform  of  a  truck  running  on  tracks.  The  machine  consists  as 
usual  of  a  ladder  hinged  to  a  tower  at  its  upper  end,  while  its 
lower  end  is  supported  by  a  boom.  The  ladder  is  provided  with 
a  double  endless  chain  carrying  steel  buckets  and  revolving  around 
two  tumblers  at  the  ends  of  the  ladder.  An  engine  providing 
power  to  the  upper  tumbler  moves  the  buckets  along  the  ladder. 


TRANSPORTATION  OF  THE  DEBRIS 


199 


The  manner  of  operating  this  apparatus  is  very  simple.  The  boat 
loaded  with  the  dredged  materials  approaches  the  machine,  the 
ladder  is  lowered  so  as  to  dig  into  the  debris,  the  engine  is  then 
started,  and  the  material  picked  up  by  the  buckets  ascends  the 
ladder  and  in  revolving  around  the  upper  tumbler  drops  into  a 
chute.  The  machine  may  be  either  firmly  mounted  on  a  scaffold 
made  up  of  heavy  timber  beams  and  located  at  some  convenient 
point  along  the  river  shores,  as  in  Fig.  68,  or  it  may  be  mounted 
on  a  platform  of  a  railroad  car  and  moved  along  tracks  placed 


FIG.  68. — Bucket  Elevator  for  Unloading  Barges. 

along  the  shores.  In  the  former  case  the  material  when  dumped 
from  the  buckets  into  the  chute  enter  into  bins  and  from  them  is 
discharged  by  gravity  into  cars  and  thus  sent  to  its  final  destination. 
With  the  other  method  material  from  the  chute  is  dumped  directly 
onto  the  ground  which  is  to  be  filled  up.  In  this  case,  it  is  necessary 
to  use  a  high  tower  so  as  to  extend  the  chute  in  order  to  dump  the 
material  at  more  distant  points. 

Sometimes,  especially  when  close  to  the  shores,  the  river  or 
canal  is  very  shallow  and  a  loaded  scow  could  not  safely  navigate 
there:  the  elevators  are  then  mounted  on  floats.  Then  the  ladder 


200 


A  TREATISE  OX   DREDGES   AXD   DREDGING 


is  placed  at  the  center  of  the  apparatus  and  is  supported  by  two 
independent  floats,  each  of  them  affording  a  firm  support  for  one 
of  the  standards  of  the  tower.  Besides,  the  floats  are  connected 
together  by  a  bridge  provided  with  a  gantry  for  raising  the  ladder. 
The  scows  enter  the  space  between  the  floats,  passing  under  the 
bridge.  The  unloading  is  very  simple.  The  ladder  that  was  raised 
to  allow  the  scow  to  enter  is  now  lowered  into  the  hold,  the  machine 
is  put  in  motion,  arid  the  buckets  filled  with  materials  travel  along 
the  ladder  and  dump  their  contents  over  the  upper  tumbler,  dis- 


FIG.  69. — Floating  Elevator  for  Unloading  Barges. 

charging  into  a  long  chute  which  delivers  the  materials  to  the  land  to 
be  filled.  The  long  chute  can  be  supported  in  the  manner  indicated 
in  the  figure,  or  when  the  elevator  is  located  too  far  from  shore 
the  chute  can  be  supported  by  means  of  another  float  and  in  the 
manner  already  described  on  page  186.  The  ladder  may  con- 
tain only  one  series  of  buckets,  like  any  ladder  dredge,  but  owing 
to  the  fact  that  the  buckets  used  are  of  small  capacity,  to  hasten 
the  unloading  operation  and  at  the  same  time  to  prevent  increasing 
the  size  of  the  buckets,  thus  producing  too  much  strain  on  the  bot- 
tom of  the  scows,  two  series  of  buckets  are  usually  mounted  on 


TRANSPORTATION   OF  THE  DEBRIS 


201 


the  same  ladder.  Fig.  69  represents  a  floating  elevator  with  single 
bucket  as  built  by  H.  Satre  &  Co.  while  Fig.  70  represents  a  floating 
elevator  with  double  buckets  used  in  the  North  Baltic  Sea  Canal 
and  built  by  A.  F.  Smulders  of  Rotterdam.  It  is  obvious  that 
in  connection  with  the  bucket  elevators  only  two  types  of  barges 
can  be  used,  and  these  are  the  open-hold  barges  and  the  deck  barges 
with  cargo  boxes. 

Other  machines  for  elevating  the  debris  from  the  barges  are 
derricks  or  cranes.    These  are  so  extensively  used  on  public  works 


FIG.  70. — Floating  Elevator  with  Double  Ladder. 

and  so  well  known  that  a  description  is  not  necessary.  They  can 
be  mounted,  either  on  a  fixed  scaffold  erected  along  the  shores 
of  the  river  or  canal,  or  on  a  float.  The  scow  with  the  dredged 
materials  is  placed  alongside  or  under  the  derrick;  the  skips  deposited 
on  deck  are  attached  to  the  hoisting  chain  of  the  derrick,  lifted  and 
swung  to  the  land.  The  skips  are  dumped  either  directly  into  the 
cars,  or  into  bins  from  which  the  material  is  loaded  into  cars  when 
required.  As  previously  stated,  this  method  of  transporting  and 
lifting  the  materials  is  very  seldom  used. 


202 


A   TREATISE  ON   DREDGES   AND   DREDGING 


Another  method  used  for  unloading  scows  is  by  means  of  a 
grab  bucket  dredge.  In  this  case  the  debris  from  the  scow  is  picked 
up  by  the  bucket,  which  can  be  of  the  clamshell  or  orange  peel 
type,  and  dumped  either  directly  on  land  or  into  cars,  running  on 
tracks  laid  parallel  to  the  shores.  This  method  cannot  be  used,  except 
when  the  difference  of  level  between  the  water  and  the  surrounding 
land  is  slight,  and  the  materials  must  be  raised  only  a  short  height. 

When  the  dredged  materials  in  the  scows  must  be  raised  to 
a  greater  height,  a  grab  bucket  attached  to  a  hoisting  and  con- 
veying machine  will  be  found  more  convenient.  The  apparatus 
in  this  case  will  consist  of  a  solid  scaffold  firmly  fixed  on  shore. 


FIG.  71. — Grab  Bucket  for  Unloading  Barges. 

On  this  scaffold  is  mounted  an  inclined  cantilever  beam  with  one 
end  projecting  well  over  the  river  so  as  to  permit  the  bucket  to 
be  over  the  scow,  while  the  other  end  extends  over  the  land.  The 
cantilever  is  inclined  toward  the  river,  thus  leaving  a  large  space 
for  the  bins  on  the  land  side.  The  grab  bucket  travels  along  the 
cantilever  suspended  to  a  small  truck.  The  bucket  is  attached  to 
the  end  of  the  hoisting  cable  and  raised  to  the  underside  of  the 
cantilever,  when  a  hauling  cable  moves  it  along  the  whole  length 
of  the  cantilever.  The  bucket  of  the  usual  capacity,  varying 
between  J  and  1  cu.yd.,  is  opened  and  closed  as  explained  for 
the  grab  dredges  when  the  bucket  is  commanded  by  a  double- 
chain  system.  The  cantilever  on  the  land  side  is  of  such  height 


TRANSPORTATION   OF  THE  DEBRIS  203 

•   f 

as  to  permit  the  construction  of  bins  for  the  temporary  deposit 
of  the  dredged  materials  when  removed  from  the  scows.  These 
bins  are  so  constructed  that  railroad  cars  running  on  standard- 
gauge  tracks  may  pass  underneath  them;  thus  the  debris  from 
the  bins  may  be  automatically  dumped  into  the  cars  to  be  sent 
to  their  final  destination.  Fig.  71  represents  one  of  these  for  unload- 
ing barges  as  used  along  the  Mississippi  River  in  connection  with 
the  sand  and  gravel  industry.  It  Was  taken  from  Engineering 
Record,  January  5,  1907.  • 


CHAPTER  XXIV 
METHODS   AND   COSTS   OF   RIVER   DREDGING 

MUCH  has  been  written  in  this  treatise  on  dredges  and  their 
adaptability  to  various  kinds  of  work.  Space  would  not  admit  of 
a  detailed  description  of  all  the  classes  of  work,  such  as  deep-sea 
dredging,  harbors,  drainage,  land  reclamation,  mining  and  river  work. 
However  a  description  is  given  in  this  chapter  of  the  improvement 
of  the  St.  Lawrence  River.  This  is  one  of  the  most  important 
engineering  works  in  America,  and  dredging  has  been  carried  on 
almost  continuously  for  nearly  70  years.  It  serves  too  as  an 
excellent  example  of  dredging,  as  the  conditions  of  the  work  and 
the  kind  of  soils  varies  and  several  types  of  machines  have  been 
used.  It  will  serve  to  bring  out  a  number  of  important  details 
regarding  dredges  and  dredging.  It  is  written  from  reports  and 
information  furnished  by  Mr.  F.  W.  Cowie,  chief  engineer  of  the  work. 

The  first  improvement  was  started  in  1844.  The  machinery 
first  used  was  built  in  Glasgow,  Scotland,  but  since  then  nearly 
all  the  dredges  have  been  built  in  Canada.  The  progress  made  in 
the  design  and  construction  of  dredges  is  aptly  illustrated  by  the 
work  done  on  this  river.  In  66  years  the  improvements  to  dredges 
have  been  phenomenal.  For  instance  a  dredge  working  in  Lake  St. 
Peter  in  1846  excavated  in  one  day  about  1200  cu.yds.  In  1888 
a  dredge  working  in  the  same  place  excavated  7200  cu.yds.,  while 
in  1906,  20,000  cu.yds.  were  frequently  excavated  in  a  day  and 
night  run. 

The  channel  of  the  river  from  Montreal  to  Father  Point,  where 
the  river  flows  into  the  Gulf  of  St.  Lawrence,  is  about  340  statute 
miles.  The  greater  part  of  the  dredging  is  done  between  Montreal 
and  Traverse,  a  distance  of  220  miles.  The  work  done  from  1844-50 
was  in  Lake  St,  Peter,  to  deepen  some  shallow  places  in  order  to 
allow  500-ton  vessels  to  reach  Montreal. 

In  1851  organized  work  was  undertaken  to  make  a  channel 
for  large  vessels  from  Montreal  to  Quebec,  160  miles.  By  1888, 

204 

I 


METHODS  AND  COSTS  OF  RIVER  DREDGING  205 


. 


for  a  distance  of  108  miles,  from  Montreal  to  Cap  a  la  Roche,  a 
depth  of  27^  ft.  at  low  water  had  been  obtained,  while  for  the  other 
52  miles  the  river  had  been  dredged  to  the  same  depth  at  half  tide. 
Prior  to  1888,  namely  from  1851-1888,  19,865,693  cu.yds.  of  material 
were  dredged  at  a  cost  for  labor  and  supplies  of  17.1  cents.,  while 
the  charge  for  plant,  shops,  repairs,  surveys  and  other  general 
expenses  was  2.7  cents,  making  a  total  of  19.8  cts.  The  work  from 
the  start  has  been  done  with  dredges  and  machines  owned  by  the 
channel  authorities  and  with  day-labor  forces. 

For  the  period  from  1889  to  1899  there  was  excavated  3,558,733 
cu.yds.,  in  widening  and  cleaning  up  the  27^-ft.  channel,  at  a  cost 
of  23.3  cts.  for  labor  and  supplies,  to  which  must  be  added  14  cts. 
for  plant,  shops,  repairs,  surveys  and  other  charges,  making  a  total 
cost  per  cu.yd.  of  37.3  cts. 

Since  1899  work  has  been  done  on  a  new  project,  namely,  a 
30-ft.  channel,  from  Montreal  to  the  Traverse,  the  distance  to  be 
actually  dredged  being  about  70  miles.  Up  to  March  31,  1908, 
about  58J  miles  were  finished,  leaving  at  that  time  11 J  miles  to 
be  dredged.  The  minimum  width  of  this  channel  is  400  ft.  in  the 
straight  portions,  and  from  500  to  750  ft.  on  the  curves  or  turns. 
The  entire  channel  has  been  widened,  with  the  exception  of  a  stretch 
in  Lake  St.  Peter.  Of  a  total  of  68,500,000  cu.yds.  of  excavation 
to  be  made  to  complete  this  project  55,517,055  cu.yds.  had  been 
dredged  up  to  March  31,  1908.  The  detail  cost  of  this  work  will 
be  given. 

The  materials  excavated  vary  exceedingly.  In  Lake  St.  Peter 
soft  blue  clay  mud  is  encountered;  at  other  places,  as  where  the  fresh 
and  salt  water  meets,  sand-bars  are  found,  of  coarse  sand;  then 
stiff  clay,  hardpan,  shale  rock,  large  boulders  and  other  materials 
are  found  at  different  localities. 

A  word  about  the  St.  Lawrence  River.  In  many  ways  it  differs 
from  most  rivers  of  the  world,  and  this  affects  the  work  of  dredging 
somewhat.  An  ordinary  river  generally  has  deep  slopes  and  grades 
near  its  source,  that  mean  great  erosion  of  the  bed  and  banks 
by  the  swift  current.  Thus  near  the  source  the  water  becomes 
saturated  with  soil,  which  is  deposited  in  the  level  stretches  of 
the  river  and  at  its  mouth,  always  interfering  with  navigation. 
When  such  rivers  are  dredged,  those  portions  fill  up  again  with 
the  fine  sediment,  thus  making  the  work  of  dredging  almost  con- 
tinuous, as  in  the  Mississippi  and  Missouri  Rivers.  The  only  other 


206  A  TREATISE  ON   DREDGES   AND   DREDGING 

method  of  keeping  this  sediment  out  of  the  river  is  to  narrow  the 
stream  and  protect  the  banks  by  revetments  in  the  flat  parts  of  the 
river,  as  these  prevent  the  stream  from  further  eroding  the  banks, 
and  the  narrowed  channel  means  a  swifter  current  that  will  keep 
the  sediment  in  suspension.  Then  at  the  mouth  of  the  river  jetties 
can  be  constructed  that  causes  the  current  to  sweep  the  channel 
clear  and  carry  the  sediment  into  the  b&y  or  ocean. 

The  source  of  the  St.  Lawrence  River  is  in  the  Great  Lakes, 
which  act  as  huge  storage  reservoirs  and  settling  basins.  Except 
for  floods  caused  by  the  melting  and  breaking  up  of  the  winter  ice 
the  fluctuations  of  the  river  are  always  gradual.  Thus  the  material 
usually  carried  by  river  water  is  deposited  in  the  settling  basins, 
this  being  the  case  even  with  the  few  streams  that  flow  into  the 
St.  Lawrence,  as  the  so-called  lakes  and  bays,  as  Lake  St.  Peter, 
act  as  settling  basins  for  such  streams.  Generally,  the  bottom  of 
the  river  is  hard,  and  although  in  many  places  this  makes  difficult 
dredging,  yet  once  dredged,  the  work  is  permanent.  The  currents 
of  the  river  are  regular,  and  although  there  is  little  danger  to  vessels 
that  navigate  the  river,  yet  the  water  at  times  becomes  rough  from 
sudden  squalls,  compelling  the  dredges  to  suspend  work  and  seek 
sheltered  places.  The  season  of  dredging  is  about  7J  months. 

As  the  material  dredged  is  dumped  into  the  river  at  places 
where  it  will  not  interfere  with  navigation,  it  is  seen  that  this  work 
does  not  theoretically  nor  practically  lower  the  level  of  the  water. 

The  following  plant  was  used  on  the  river  during  the  season 
of  1907: 

6  elevator  dredges. 

1  hydraulic  dredge  with  23  double  pontoons,  floating  a  2300-ft. 
double  line  of  pipe,  and  2  winch  scows. 

1  twin-screw  self-containing  hydraulic  dredge. 

1  twin-screw  sea-going  pump  dredge. 

1  ice-breaking  and  sweeping  tug  and  1  testing  or  sounding 
scow  used  with  it. 

I  inspection  tug. 

II  tugs  for  serving  dredges. 
4  coal  barges. 

1  coal  scow. 

2  stone  lifters. 

6  lodging  scows. 
14  hopper  scows. 


METHODS  AND  COSTS   OF  RIVER   DREDGING  207 

As  the  dredging  is  completed  the  channel  is  swept,  so  that  the 
depths  dredged  are  reliable  and  available.  A  twin-screw  river  steamer 
and  a  testing  scow  have  been  used  as  a  sweeping  plant,  but  now  a 
new  ice-breaking  and  sweeping  tug  has  been  designed  for  this 
purpose.  In  the  Detroit  River  Improvement  a  drag,  consisting 
of  a  bevel-shaped  iron-shod  beam  loaded  heavily  with  scrap  iron 
and  suspended  from  one  end  of  a  dump  scow  is  used  to  sweep  the 
bottom  where  earth  has  been  removed.  When  dragging  this  con- 
trivance over  the  dredged  area,  the  cutting  beam  is  usually  set 
about  one  foot  below  the  required  depth.  This  tool  is  effective  in 
soft  material  only. 

One  of  the  six  elevator  dredges  was  built  in  1894,  one  in  1897, 
two  in  1900,  one  in  1901  and  one  in  1902.  These  dredges  are  from 
148  to  168  ft.  long;  have  beams  of  30  to  34  ft.,  and  an  average 
draft  of  from  8  to  11  ft.,  and  a  working  depth  from  42.5  to  45  ft. 
The  buckets  are  of  a  capacity  up  to  1  cu.yd.  and  can  excavate  from 
1000  to  3500  cu.yds.  of  fairly  hard  material  per  day.  Two  of  them 
have  steel  hulls,  the  rest  wooden  ones.  These  dredges  have  all 
been  built  by  the  Canadian  Government  at  their  Sorel  yards. 

In  consideration  of  the  character  of  the  shale  rock,  of  the  strong 
current,  and  of  the  fact  that  the  work  must  be  carried  on  without 
interrupting  navigation  the  elevator  dredge  is  well  adapted  for 
this  work.  A  powerful  dipper  dredge  may  tear  up  a  certain  quantity 
of  soft  rock  more  quickly,  without  stopping  to  make  a  clean,  even 
bottom.  Chisel  cutters  and  blasting  plants  may  break  up  harder 
material,  but  taking  everything  into  consideration  this  type  of 
plant  is  particularly  well  designed  for  good,  clean  work,  without 
interrupting  navigation.  Only  the  best  machinery  can  stand  up 
under  the  constant,  steady  work  in  the  hard  material  encountered. 
This  is  evidenced  by  the  fact  that  the  buckets  suffer  much  from 
each  season's  work.  The  dredge  "La  Fontaine/'  built  in  1901, 
after  three  seasons'  work  had  a  complete  new  set  of  solid  steel 
rock  buckets  put  into  her.  The  dredge  "  Baldwin  "  had  her  buckets 
rebuilt  after  two  seasons'  work.  At  the  end  of  the  season  of  1907 
the  total  cost  of  renewals  and  repair  on  buckets  alone  was  $71,826.12. 
This  makes  an  average  of  about  $20,000  per  dredge  for  new  sets  of 
buckets.  The' "  La,urier, "  built  in  1897,  had  a  new  set  of  J-cu.yd. 
hardpan  buckets  put  in  her  in  1906,  at  a  cost  of  $19,336. 

The  hydraulic  dredge  used  is  the  well-known  "J.  Israel  Tarte, " 
designed  by  Mr.  A.  W.  Robinson.  This  dredge  was  designed  for 


208  A  TREATISE  ON   DREDGES  AND   DREDGING 

work  in  Lake  St.  Peter,  and  in  a  paper  delivered  before  the  Canadian 
Society  of  Civil  Engineers  Mr.  Robinson  states  the  following  con- 
ditions wrere  considered  in  her  design  and  building  : 

"It  must  be  able  to  make  a  cut  900  ft.  wide  at  one  time  and 
5  ft.  to  10  ft.  thick  at  one  cut. 

"It  must  leave  a  clean  and  level  bottom  and  cut  mechanically 
the  entire  area,  as  the  material  is  blue  clay  and  will  not  run  or  wash 
like  sand. 

"It  must  deliver  the  material  sufficiently  far  to  one  side  of  the 
channel  to  avoid  any  risk  of  washing  back  again. 

•  "The  floating  pipe  line  must  be  so  arranged  that  it  will  freely 
permit  of  the  movements  of  the  dredge,  and  that  it  will  withstand 
the  wind  and  waves  due  to  the  locality,  which  are  severe  at  times. 

"The  dredge  must  be  so  worked  that  it  will  not  obstruct  the 
channel  for  passing  ships. 

"  The  anchorage  and  movements  of  the  dredge  must  be  so  arranged 
that  the  feed  will  be  continuous  and  uniform. 

"The  capacity  to  be  a  working  rate  of  2000  cu.yds.  per  hour. 

"The  dredge  must  have  ample  coal  supply,  also  provision  for 
a  double  crew." 

The  contract  price  for  this  dredge  was  $163,800,  not  including 
the  discharge  price  or  winches  nor  the  alterations  made.  The 
dredge  was  built  by  the  Polsom  Iron  Works  of  Toronto,  Ont.,  in 
1901  and  tested  that  year,  but  was  not  put  to  work  until  June,  1902. 
Previous  to  this  dredging  had  been  done  in  Lake  St.  Peter  by  elevator 
dredges. 

During  the  season  of  1886  one  such  dredge  excavated  886,710 
cu.yds.  for  $25,723,  or  a  cost  for  labor,  coal,  etc.,  of  2.9  cts.  The 
dredge  "Lady  Aberdeen,"  with  1  cu.yd.  buckets  during  the  season 
of  1901,  excavated  in  21  days  at  a  cost  of  $3054.88,  120,600  cu.yds., 
the  unit  cost  being  2.53  cts.  The  actual  working  time  was  246  hours, 
thus  an  hourly  output  of  490  cu.yds.  was  attained. 

The  first  month,  June,  1902,  the  "J.  Israel  Tarte"  was  put  to 
work;  she  excavated  93,750  cu.yds.  This  was  accomplished  in 
41J  hours.  Each  month  the  output  increased  as  the  crew  became 
accustomed  to  the  work.  Thus  in  September  580,000  cu.yds.  were 
dredged,  in  October  600,000  cu.yds.  The  area  covered  in  Septem- 
ber was  7800  lin  ft.  by  325  ft.,  to  an  average  depth  of  5  ft.  In 
October  a  strip  of  the  same  width  and  depth  but  8000  ft.  long  was 
done.  The  dredge  worked  126  working  days  in  the  season  of  1903, 


METHODS  AND   COSTS   OF   RIVER  DREDGING  209 

excavating  2,671,750  cu.yds.,  scow  measurement,  giving  a  daily 
rate  of  21,200  cu.yds.  During  the  month  of  September,  1903,  the 
dredge  excavated  757, 100  in  25  days  or  552  hours,  making  an  average 
rate  of  1646  cu.yds.  per  hour,  or  30,280  cu.yds.  per  day.  During 
the  season  of  1904  in  92  days  the  "Tarte"  dredged  1,123,125  cu.yds. 
at  a  total  cost  of  $79,302.02,  or  7.06  cts.  per  cu.ycl.  In  1905,  1,984,- 
510  cu.yds.  were  moved,  costing  $117,668.03,  or  5.92  cts.  per  cu.yd. 
This  work  was  done  in  160  days.  For  the  season  of  1906,  in  105 
working  days  1,358,560  cu.yds.  were  excavated,  costing  $86,533.82 
or  6.36  cts.  per  cu.yd. 

The  "J.  Israel  Tarte"  is  160  ft.  in  length,  42  ft.  beam,  with  a 
draft  of  6  ft.  (see  Fig.  34).  The  suction  frame  is  80  ft.  long,  giving 
a  possible  working  depth  of  45  ft.  The  discharge  pipe  is  36  in.  in 
diameter.  The  four  boilers  are  of  the  marine  type,  carrying  160 
Ibs.  pressure.  The  rotary  cutter  is  9  ft.  long  and  9  ft.  6  in.  in  diameter. 
There  are  four  steel  blades  at  the  apex  and  8  at  the  throat  (see  Fig. 
27) .  The  blades  are  designed  so  that  the  clay  does  not  clog  up  the 
throat.  The  cutter  is  operated  by  a  pair  of  double  tandem  engines 
of  300  H.P.  (see  Fig.  26). 

Near  the  close  of  the  season  of  1903  one  of  the  boilers  on  this 
dredge  exploded,  killing  two  men  and  injuring  the  dredge.  It 
took  four  months  to  make  the  repairs.  Four  new  boilers  were 
placed  in  her.  These,  with  a  new  system  of  steam  piping,  erecting 
the  smokestacks  and  work  on  her  cabin  cost  $27,644.11.  At  the 
end  of  1905  a  general  overhauling  was  given  the  machinery  and 
boilers.  Thus  the  dredge,  as  it  now  stands,  cost  for  hull,  machinery, 
5-ft.  pipe  line,  as  altered  and  improved,  about  $400,000.  The  annual 
repairs  have  varied  from  $8000  to  20,000,  or  a  little  more  than 
5  per  cent  of  the  cost  of  the  machine. 

The  annual  repairs  to  one  of  the  ladder  or  elevating  dredges 
used  on  the  St.  Lawrence,  with  its  necessary  outfit,  averages  about 
$10,000.  It  cost  about  $40,000  per  year  to  operate  such  a  dredge, 
and  about  twice  that  amount  to  operate  a  hydraulic  dredge  such 
as  the  "Tarte."  It  is  estimated  that  the  entire  dredging  plant 
used  on  the  St.  Lawrence  River  cost  about  $2,000,000.  This  is  exclu- 
sive of  a  well-equipped  shop  maintained  by  the  Canadian  Govern- 
ment at  SoreL  for  building  and  repairing  dredges,  tugs,  scows  and 
other  things  needed  both  on  the  St.  Lawrence  and  for  other  dredg- 
ing work. 

In  1906  a  hydraulic  hopper  dredge  was  purchased  and  put  to 


210  A  TREATISE  ON  DREDGES   AND   DREDGING 

work  in  the  channel  below  Quebec.  This  machine,  the  "  Galveston," 
is  233  ft.  long;  39  ft.  beam,  and  of  14  ft.  9  in.  draft  when  loaded 
with  1800  tons.  The  hopper  capacity  is  1400  cu.yds.  The  machine 
dredges  to  a  depth  of  55  ft.  and  can  pump  1350  cu.yds.  in  45  minutes. 
The  price  paid  for  this  dredge,  built  in  1904,  was  $146,000.  It  was 
brought  from  New  Orleans  to  Quebec  in  29  days,  the  expenses  of 
the  trip  for  docking,  repairing,  wages,  provisions,  stores,  etc.,  amount- 
ing to  $10,942.14.  This,  exclusive  of  $4,574.17  insurance.  Another 
dredge  of  this  type,  the  "  Beaujeu, "  the  largest  dredge  in  Canada, 
has  also  been  added  to  the  fleet. 

About  500  men  are  employed  on  this  work.  These  men  have 
been  born  and  bred  as  sailors,  and  are  from  Sorel  or  some  of  the 
parishes  bordering  on  the  St.  Lawrence  River.  The  majority  have 
been  in  the  service  since  boyhood.  The  senior  captain  of  the  fleet 
makes  the  statement,  with  a  great  deal  of  pride,  that  he  has  never 
earned  a  cent  in  any  other  service.  The  careful  training  of  the  men 
has  added  much  to  the  success  of  the  work,  as  great  care  and  patience 
are  needed  as  well  as  continual  watching,  made  necessary  by  the 
passing  vessels. 

A  captain  is  in  charge  of  the  vessel  and  an  engineer  of  the  machin- 
ery. The  rest  of  the  crew  is  divided  into  two  watches,  working  in 
6-hour  shifts,  each  watch  working  two  shifts  per  24-hour  day.  Each 
week  132  hours  are  worked  from  midnight  Sunday  until  noon  Satur- 
day, only  two  holidays  being  observed:  Dominion  Day  and  Labor 
Day.  The  captain  boards  the  men  by  contract.  Most  of  the 
dredges  and  tugs  are  fitted  up  with  quarters  for  the  men,  but  in 
addition  to  this  there  are  six  scows  with  lodging  accommodations  on 
them. 

The  following  is  a  list  of  the  crew  and  the  wages  paid  to  them 
on  the  ladder  dredges: 


1  captain     

$80  per  r 

nonth 

1  engineer 

90 

4  officers                

$40  to  65 

2  engineers 

.    .   40  to  60 

10  sailors  
6  firemen 

28 
30 

1  watchman              

28 

3  women  cooks  .  . 

.    12  to  18        " 

The  crew  and  their  salaries  for  work  on  a  hydraulic  dredge  are 
as    follows : 


METHODS  AND  COSTS  OF  RIVER  DREDGING  211 


1  captain $100  per  month 

1  engineer 105 

4  officers 50  to  75 

2  engineers 55  to  70 

2  scowmen  and  carpenters 50 

12  sailors 28 

6  firemen 32 

2  greasers 40 

1  watchman 28 

4  women  cooks 12  to  18 


The  men  are  not  charged  for  their  board,  which  would  no  doubt 
mean  an  increase  of  about  $12  per  man  per  month.  The  crews 
of  the  tugs  are  paid  similar  salaries.  Large  crews  are  necessary 
to  handle  with  safety  the  loaded  scows.  During  the  closed  season, 
for  4J  months,  only  enough  engineers  and  firemen  are  retained  to 
look  after  the  vessels.  In  considering  the  cost  of  this  work  one 
must  keep  in  mind  that  the  wages  paid  are  small  and  the  hours 
worked  long.  If  this  same  work  was  being  done  for  the  United 
States  Government  either  by  contract  or  day  labor  three  shifts 
would  have  to  be  Worked,  adding  from  10  to  15  men  to  the  crews 
and  higher  wages  would  have  to  be  paid.  The  records,  though,  are 
of  value,  as  they  extend  over  a  long  period  of  time,  and  costs  are 
given  as  to  repairs  and  maintenance  and  other  details  that  are 
generally  difficult  to  obtain. 

The  method  of  operation  is  of  interest.  The  river  is  divided  into 
five  divisions  so  as  to  organize  the  work  for  supervision  and  for  the 
greatest  efficiency.  The  "Galveston"  is  worked  continually  below 
Quebec  and  the  "Tarte"  in  Lake  St.  Peter,  but  the  other  dredges 
are  moved  from  division  to  division  according  to  the  class  of  material 
to  be  excavated  or  to  the  urgency  of  the  work.  The  dredges  stop 
only  for  repairs,  for  moving  from  place  to  place,  for  bad  weather 
or  to  allow  vessels  to  pass.  In  only  a  few  cases  are  records  given  of 
these  delays.  Coal  is  supplied  by  barges  without  stopping  the 
work.  Much  would  be  added  to  the  cost  data  given  if  detail 
records  of  delays  could  be  shown. 

The  elevator  or  ladder  dredges  load  scows,  one  tug  with  two 
scows-  and  a  spare  scow  serving  each  dredge.  The  average  distance 
the  excavated  material  is  hauled  is  less  than  one  mile.  The  scows 
hold  300  cu.yds.,  and  as  it  takes  a  tug  15  minutes  to  haul  one  of 
these  away,  dump  it  and  return,  it  is  possible  with  this  service  to 
take  away  1200  cu.yds.  per  hour,  more  material  than  a  dredge  is 
likely  to  excavate.  These  dredges  are  held  to  their  work  by  a  long 


212 


A  TREATISE  ON    DREDGES   AND   DREDGING 


bow  cable  and  two  cables  on  each  side  of  the  vessel,  see  Fig.  71. 
This  permits  a  vessel  to  make  a  wide  radial  cut  and  to  easily  clear 
passing  boats. 

The,"Tarte"  is  held  in  the  same  manner,  which  allows  it  to 
work  from  one  side  of  the  channel  to  the  other.  To  allow  vessels 
to  pass,  one  set  of  side  lines  are  slackened  so  that  they  drop  on 
the  river  bottom  and  the  passing  boats  go  over  them.  The  pipe 
line,  which  is  about  half  a^  mile  long,  has  ball  and  socket  spring 
joints  between  every  pontoon.  These  pontoons  are  made  of  two 
cylindrical  air  chambers,  holding  100  ft.  of  discharge  pipe  between 
them.  The  discharge  end  of  the  pipe  is  held  in  place  by  a  winch 
scow.  When  the  dredge  works  on  the  side  of  the  channel  on  which 
the  discharge  is  made,  the  pipe  assumes,  by  floating  on  the  pontoons, 
a  decided  curve,  but  as  the  dredge  passes  to  the  other  side  of  the 
channel  the  pipe  line  straightens  out,  the  operation  only  varying 
the  discharge  end  slightly,  see  Fig.  36. 

Both  style  of  dredges  work  to  a  uniform  bottom,  cleaning  up 
as  they  go.  When  boulders  are  encountered  the  stone  lifters  are 
used.  In  one  case,  when  the  cutter  head  of  the  "Tarte"  broke  off, 
it  was  recovered  with  one  of  these  boats.  In  addition  to  the  sweep- 
ing of  the  channel  after  dredging,  the  shallow  channels  are  swept 
once  a  year. 

Cost  Data.  In  giving  the  following  tables  of  costs,  everything 
is  included  except  interest  on  the  capital  and  depreciation.  The 
tables  are  self  explanatory.  The  item  of  repairs  includes  keeping 
the  plant  in  good  order,  but  not  new  or  improved  machinery. 

TABLE    I 


Year. 

Number  of 
Cubic  Yards 
(Scow  Measure). 

Wages,  Supplies, 
etc. 

New  Plant 
Rebuilding  Shop 
Surveys,  etc. 

Cost  per  Cubic 
Yard,  Wages, 
Supplies,  etc. 

1899-1900 

1,107,894 

$100,191.01 

$265,270.78 

$0.090 

1900-1901 

2,479,385 

136,680.83 

287,049.04 

0.055 

1901-1902 

3,098,350 

185,429.80 

479,731.47 

0.060 

1902-1903 

6,544,605 

255,766.55 

277,703.50 

0.040 

1903-1904 

4,619,260 

276,958.59 

308,765.44 

0.060 

1904-1905 

2,716,220 

311,087.93 

266,460.33 

0.115 

1905-1906 

4,047,530 

431,738.30 

125,107.37 

0.106 

1906-1907 

3,001,010 

302,677.37 

80,613.26 

0.102 

Table  I,  gives  for  a  term  of  eight  years,  material  excavated,  and 
total  cost  for  wages,  supplies,  new  plant  surveys  and  other  details. 


METHODS  AND  COSTS   OF    RIVER  DREDGING 


213 


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A  TREATISE   ON  DREDGES  AND   DREDGING 


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216  A  TREATISE  ON   DREDGES  AND  DREDGING 

-  Table  II,  gives  the  work  done  by  each  of  seven  dredges  for 
three  seasons.  Class  of  material  excavated,  total  cost,  cost  per 
cu.yd.,  number  of  days  worked,  and  percentage  of  actual  time  work. 
Time  lost  by  repairs,  moving,  bad  weather,  clearing  traffic  and 
other  delays,  amounting  to  more  than  one-third  of  total  time 
worked. 


CHAPTER  XXV 
DREDGING   FOR    METALS 

DREDGES  are  used  for  mining  precious  metals,  especially  gold, 
tin,  diamonds  and  platinum.  At  first  dredges  were  used  only  when 
metals  were  recovered  from  the  bottoms  of  rivers,  but  it  was  found 
that  by  excavating  a  small  pond  or  lagoon  and  placing  a  dredge  in 
it,  alluvial  deposits  could  be  mined  at  a  low  cost  by  dredges.  This 
is  now  done  in  many  parts  of  the  world. 

Tin  Dredging.  For  tin  dredging,  hydraulic  dredges  are  used. 
Much  of  this  class  of  mining  is  done  in  Australia  and  New  Zealand. 
Elevator  or  ladder  dredges  can  be  used,  and  when  gold  and  tin  are 
dredged  together  they  are  sometimes  used,  but  with  difficulty,  as 
the  specific  gravity  of  the  two  metals  varies  much.  One  authority 
states  that  the  ladder  dredge  for  stream  tin  is  efficient,  but  he  has 
little  faith  in  it  when  there  is  much  overburden. 

Platinum  Dredging.  Dredging  for  platinum  is  done  in  the 
Urals  in  Russia  and  also  in  Siberia.  Ladder  or  elevator  dredges 
have  been  used  for  some  years.  Those  first  used  were  machines 
bought  second  hand  that  had  been  engaged  in  excavating  the  Kiel 
Canal.  These  dredges  made  some  money,  especially  when  the  price 
of  platinum  was  high,  owing  to  the  cheap  labor  that  could  be  obtained, 
but  as  they  were  not  built  for  mining  purposes  they  were  poorly 
suited  to  the  work.  Other  dredges  of  the  ladder  type,  designed 
for  the  purpose,  have  been  built  and  are  operated  much  cheaper. 
The  dredges  are  used  to  excavate  the  overburden  and  also  the  gravel 
containing  the  platinum.  For  this  purpose  two  dredges  are  some- 
times used  together.  The  overburden  being  deep,  two  or  three 
times  as  much  material  must  be  handled  by  the  dredge  as  when 
working  the  gravel.  Accordingly  a  large  capacity  dredge  is  used 
for  the  overburden  and  a  small  one  for  the  gravel.  In  this  way 
the  two  classes  of  work  are  done  simultaneously.  During  the  year 
1908,  64  dredges  were  worked  in  this  business. 

Diamond  Dredging.  Ladder  dredges  are  also  used  for  diamond 
mining.  The  dredges  save  diamonds  on  its  screens  and  jigs,  which 

217 


218  A   TREATISE  ON  DREDGES   AND  DREDGING 

are  located  at  the  stern.  The  dredges  are  of  the  close  bucket  type, 
and  there  is  said  to  be  a  great  chance  for  improvement  on  the  diamond- 
saving  end.  Such  dredging  is  now  being  done  in  several  parts  of 
the  world. 

Gold  Dredging.  Dredging  is  done  more  extensively  for  gold 
than  for  any  other  metal  or  precious  stone,  and  much  has  been 
written  on  the  subject.  It  is  impossible  to  fully  cover  the  subject 
here. 

Numerous  kinds  of  dredges  have  been  used  and  are  being  used 
for  gold  dredging,  among  them  being  the  suction  and  hydraulic 
power  dredge,  the  dipper,  ladder  and  the  submerged  jet  dredge. 

It  is  claimed  that  the  hydraulic  suction  dredge  is  not  efficient,  as 
the  grains  of  gold,  on  account  of  their  great  weight,  drop  to  the  bottom, 
even  when  rotary  cutters  are  used  on  the  suction  pipe.  However, 
they  are  used  in  some  sections  and  in  some  soils  with  fairly  good 
results.  For  instance  when  the  grains  of  gold  are  exceedingly 
small  and  found  entirely  in  coarse-grained  sand  the  suction  dredge 
has  cleaned  up  the  gold.  Also  when  the  gold-bearing  gravel  or 
sand  is  underlaid  with  fissured  rock,  so  that  much  of  the  gold  cannot 
be  reached  with  buckets,  the  suction  dredge  has  cleaned  up  such 
bottoms.  Mr.  Henry  G.  Granger  advocates  the  use  of  a  hydraulic 
suction  dredge  for  gold  mining,  and  in  a  paper  before  the  Am.  Inst. 
of  Mining  Engineers  gives  the  specifications  for  such  a  dredge  with 
a  capacity  of  1000  cu.yds.  per  hour,  capable  of  raising  large  boulders. 
One  consideration  against  hydraulic  suction  dredges  is  the  sup- 
ply of  water  and  the  power  needed.  In  bucket  dredging,  under 
favorable  conditions,  about  one-eighth  part  of  water  to  one  part  of 
material  is  lifted,  while  in  centrifugal  pump  elevating,  at  least 
fifteen  parts  of  water  to  one  of  material  have  to  be  raised,  this 
being  necessary,  according  to  Mr.  H.  L.  Lewis,  as  the  water  has  to 
be  applied  for  treatment  of  the  gravel  in  addition  to  keeping  every- 
thing in  a  state  of  solution  for  successful  elevation.  It  is  evident 
that  this  means  more  power,  and  shows  the  necessity  of  a  large 
amount  of  water. 

The  dipper  and  grapple  dredges  have  been  used  for  gold,  but 
they  are  illy  adapted  to  the  work,  as  they  disturb  the  gravel  in  digging 
so  that  much  of  the  gold  sinks  to  the  bottom  and  is  lost.  It  is  also 
impossible  to  construct  a  bucket  that  is  watertight,  consequently 
the  gold  collected  at  the  bottom  of  the  bucket  is  readily  lost  through 
the  cracks.  Likewise  as  they  are  intermittent  machines  they  deposit 


DREDGING  FOR  METALS  219 

'M 

too  much  material  at  one  time,  and  there  is  a  long  interval  between 
the  loads. 

The  hydraulic  power  dredge  is  used  for  gold  dredging  in  New 
Zealand.  It  is  known  as  the  O'Brien  Patent  Hydraulic  Power  Dredge. 
Water  is  supplied  at  sufficient  elevation  to  give  gravitation  pressure 
to  a  Pelt  on  wheel  for  operating  a  ladder  dredge.  Thus  this  power 
is  used  instead  of  steam  or  electricity.  This  motive  power  saves 
in  the  first  cost  of  construction  in  boilers  and  engine,  fuel,  engi- 
neers and  maintenance  expenses.  When  gravitation  pressure  can 
be  obtained,  this  system  can  dredge  and  treat  gravel  at  a  much 
cheaper  cost  than  steam  power. 

Another  dredge  used  in  gold  mining  in  New  Zealand  and  Aus- 
tralia is  the  Johnson  Submerged  Jet  Dredge.  The  principle  is  that 
of  the  hydraulic  elevator  adapted  to  the  requirements  of  a  dredge, 
and  consists  of  ordinary  pontoons  divested  of  boiler,  engine  and 
bucket  ladder,  these  being  replaced  by  a  hydraulic  ally-driven  Pelton 
wheel  to  work  winches,  and  a  hydraulic  elevator  in  place  of  a  bucket 
ladder  to  raise  materials.  The  pressure  is  from  gravitation  of  water. 
The  theoretical  supply  of  the  elevator  is  1000  tons  per  hour. 

In  Chapter  V  is  mentioned  a  dredge  used  for  gold  mining  in 
California,  from  which  a  caisson  is  lowered  to  the  river  bed,  and  the 
water  pumped  from  it.  Then  men  enter  this  caisson  and  by  hand 
excavate  the  sand  and  gravel  containing  the  gold. 

The  DuBois  hydraulic  dredge  is  also  used.  In  this  dredge  a 
caisson  is  dropped  to  the  river  bottom  and  the  suction  pipe  is  let 
down  into  the  caisson.  A  diver  going  down  on  the  outside  of  the 
caisson  enters  it,  and  stirs  up  the  gravel,  causing  it  to  enter  the 
suction  pipe.  It  is  stated  that  in  this  manner  the  fine  particles 
of  gold  cannot  float  away.  Under  favorable  conditions  the  diver 
can  remain  under  water  several  hours. 

Ladder  Dredges.  The  ladder  dredge,  taking  up  the  material 
from  the  bottom  with  a  minimum  of  agitation  and  working  slowly 
and  steadily  is  to-day  considered  the  best  for  gold  dredging.  Besides, 
the  buckets  retain  fully  their  content,  carry  a  quantity  of  water  to 
facilitate  the  work  of  washing,  and  deliver  the  material  amidships  in 
a  continuous  small  stream.  For  these  reasons  the  ladder  dredge 
has  always  been  recognized  as  the  ideal  type  of  dredge  for  gold 
mining. 

The  ladder  dredge  employed  in  mining  consists  of  three  different 
parts,  which  are:  (a)  the  ladder  dredge  for  the  excavation  of  the 


220  A  TREATISE  ON  DREDGES   AND   DREDGING 

materials  from  the  bottom ;  (6)  the  apparatus  for  washing  the  debris 
and  collecting  the  gold;  (c)  the  conveyor  for  the  disposal  of  the 
tailings.  Each  one  of  these  will  be  described  separately,  but  all 
are  mounted  on  a  single  pontoon. 

The  pontoon  of  a  placer  dredge  is  designed  to  work  in  shallow 
water  and  consequently  is  built  with  a  flat  bottom  in  order  to  have 
the  least  draft.  It  is  provided  with  a  central  well  for  the  ladder  and 
the  walls  of  the  pit  are  firmly  held  together  by  the  truss  of  a  gantry 
used  for  the  raising  and  lowering  of  the  ladder.  The  pontoon  is  gener- 
ally built  of  wood,  but  when  the  dredge  must  be  shipped  to  distant 
points  or  where  skilled  labor  is  scarce,  the  pontoon  is  made  of 
steel  plates  and  girders  built  up  in  sections  of  such  weight  as  to 
be  easily  transported  and  joined  together.  About  the  center  of 
the  pontoon  is  located  the  tower  supporting  the  upper  end  of  the 
ladder. 

The  ladder  is  built  up  of  steel  beams  and  plates  riveted  together 
and  forming  a  solid  support  for  the  loaded  buckets  that  slide  on 
its  upper  surface.  To  facilitate  the  sliding  several  rollers  are  intro- 
duced. The  lower  end  of  the  ladder  carries  the  tumbler  of  polygonal 
shape,  around  which  revolve  the  buckets,  while  as  usual  the  driving 
tumbler  is  at  the  upper  end  of  the  ladder.  Ladders  are  made  of 
different  lengths,  varying  with  the  depth  at  which  the  dredge  is 
designed  to  work.  In  any  case  it  is  preferable  to  have  the  ladder 
of  such  length  as  to  work  under  an  angle  of  45°.  Buckets  are 
made  from  3  to  13  cu.ft.  capacity.  The  Bucyrus  Co.  build  placer 
dredges  of  three  sizes,  having  buckets  of  3,  5,  and  7J  cu.ft.  capacity 
respectively.  Buckets  are  constructed  of  steel  plates  reinforced  at 
the  mouth  by  another  steel  plate  of  greater  thickness;  they  are 
built  with  wide  mouth  in  order  that  their  contents  may  fall  more 
rapidly  when  the  point  of  discharge  is  reached.  In  some  dredges 
the  buckets  are  attached  one  to  another  so  as  to  form  a  continuous 
series  succeeding  each  other  on  the  consecutive  faces  of  the  revolv- 
ing tumbler.  In  other  dredges  the  buckets  are  alternated  with 
the  links  of  the  chain  so  that  a  bucket  and  a  link  succeed  each 
other  upon  the  consecutive  faces  of  the  tumbler.  The  links  are 
made  of  solid  steel  bars  connected  by  steel  pins.  The  bucket  chain 
moves  along  the  ladder  owing  to  the  revolving  of  the  driving 
tumbler  being  driven  by  special  engines  and  the  power  transmitted 
in  any  one  of  the  ways  indicated  in,  the  general  discussion  of  the 
ladder  dredge.  The  engine  for  lifting  the  ladder  and  other 


,  DREDGING  FOR  METALS  221 

• 

machinery  is  also  similar  to  those  employed  in  the  ladder  dredges 
of  equal  capacity. 

The  appliances  used  for  the  treatment  of  the  dredged  materials 
can  be  divided  into  two  classes,  namely,  the  screen  and  elevator 
and  the  sluice-box.  The  former  is  provided  with  a  screen  through 
which  the  material  raised  is  washed  onto  tables  and  discharged  astern 
of  the  dredge  in  a  semicircular  chute.  The  coarser  material  passes 
out  of  the  screen  into  a  tail  chute  also  to  be  deposited  astern, 
either  by  passing  over  a  sluice  run  or  being  conveyed  in  the  trays 
of  a  tailings  elevator.  The  sluice-box  dredge  is  the  one  in  which 
the  gold  is  caught  in  a  long  sluice  run,  fitted  with  ripples,  into  which 
the  buckets  tip  their  burden. 

In  the  screen  type  of  dredge  the  buckets  discharge  the  material 
into  a  hopper,  through  which  it  passes  into  either  a  revolving  or 
shaking  screen  of  sufficient  size  and  length  to  enable  it  thoroughly 
to  screen  and  wash  the  most  difficult  material.  The  revolving  screen 
is  usually  made  16  or  17  ft.  long  and  54  in.  in  diameter  and  built 
with  a  frame  of  steel  rings  and  perforated  steel  plates  so  arranged 
that  they  can  be  easily  renewed  when  worn  out  without  removing 
the  entire  screen.  The  screen  is  mounted  on  adjustable  steel  rollers 
on  a  pitch  of  1  in.  to  the  foot  and  is  driven  by  special  shafts  and  gears 
connected  with  the  main  engine.  Streams  of  water  are  introduced 
into  the  upper  end  of  the  screen  to  wash  the  material  as  soon  as 
it  enters;  water  is  supplied  by  a  centrifugal  pump  operated  by  a 
special  engine.  In  the  screen  all  the  fine  materials  being  washed 
will  fall  through  the  holes  while  the  stones  and  the  coarse  materials 
will  pass  out  of  the  lower  end  and  be  deposited  on  the  banks  by 
means  of  an  elevator  or  other  device.  The  gold,  together  with  the 
materials  and  water  falling  beneath  the  screen,  are  collected  in  a 
specially  constructed  box  which  will  equally  distribute  the  materials 
upon  the  gold-saving  tables.  These  can  be  made  of  different  designs, 
but  as  a  rule  are  constructed  of  steel  plates  and  angles.  They  can 
be  built  14  ft.  long  and  12  ft.  wide,  made  in  four  widths  of  3  ft.  each 
stepped  one  above  another  with  division  plates  between  them. 
The  tables  have  an  inclination  of  1  in  10  and  are  covered  with  some 
fibrous  substance  held  down  by  strips  of  expanded  metal  acting  as 
ripples.  Besides  the  water  from  the  screen ,  which  is  conveyed  onto 
the  gold-saving  tables,  together  with  the  materials,  to  facilitate 
the  .washing  operations  additional  water  is  supplied  by  a  special 
pipe  whose  flow  on  each  division  is  regulated  by  a  sliding  door. 


DREDGING  FOR  METALS  223 

The  tables  empty  into  a  chute  of  semicircular  cross-section  running 
out  over  the  stern  of  the  dredge.  The  gold  that  has  not  passed 
through  the  screen  perforation  onto  the  gold-saving  tables  is  collected 
in  the  sluice-box.  This  can  be  made  24  ft.  long,  3  ft.  wide  and  18  in. 
deep,  fitted  with  ripples  placed  above  mattings  made  of  some  fibrous 
matter  and  discharging  into  the  semicircular  chute. 

The  stones,  gravel  and  other  materials,  after  having  been  thor- 
oughly washed  out  in  the  revolving  screen,  come  out  from  its  lower 
end  and  by  means  of  a  conveyor  are  deposited  at  sufficient  distance 
and  height  for  stacking  purposes.  Fig.  72  shows  the  side  view 
and  plan  of  a  placer  dredge  with  revolving  screen  as  built  by  the 
Bucyrus  Company  of  South  Milwaukee,  Wis. 

When  the  material  is  finely  divided,  instead  of  a  revolving  screen 
shaking  screens  are  employed.  As  in  the  dredge  previously  described, 
the  material  is  delivered  into  a  hopper,  through  which  it  is  conveyed 
to  shaking  screens  of  sufficient  size  to  handle  the  largest  stones 
that  can  be  brought  up  in  the  buckets,  and  of  sufficient  length  to 
thoroughly  screen  and  wash  the  material  from  a  series  of  openings 
above.  Small  streams  of  water  are  projected  upon  all  parts  of  the 
screen,  washing  and  disintegrating  the  material  before  the  finer 
particles  pass  through  to  the  gold-saving  tables.  The  coarser  material 
is  discharged  at  the  lower  end  of  the  screen  into  a  hopper  leading 
to  a  belt  conveyor  or  tailings-stacker.  The  fine  material  passes 
through  the  screens  into  a  distributor,  placed  beneath  the  screens 
and  above  the  gold-saving  tables.  The  object  of  this  is  to  distribute 
the  material  evenly  over  the  tables.  These  tables  are  fitted  with 
ripples,  or  such  other  devices  a<s  may  be  best  adapted  to  the  char- 
acter of  the  gold.  The  material  which  passes  over  the  tables  is 
carried  into  sluice-boxes  which  lead  aft  to  a  point  about  20  ft. 
beyond  the  stern  of  the  dredge.  These  sluice-boxes  are  also"  fitted 
with  ripples.  Fig.  73  shows  the  plan  and  elevation  of  the  placer 
dredge  with  shaking  screen  built  by  the  Bucyrus  Company  of  South 
Milwaukee,  Wis. 

AVhen  the  gravel  or  the  gold-bearing  material  is  very  fine  the 
treatment  by  the  sluice-box  method  is  employed.  Then  the  dredged 
material  in  tipping  over  the  upper  tumbler  of  the  ladder  goes 
through  a  drop  plate,  discharging  into  a  long  sluice  which  runs  aft 
for  the  length  of  the  dredge  and  over  the  stem.  The  length  of 
the  box  will  depend  on  the  position  of  the  tumbler  framing,  and 
the  height  to  which  the  material  is  to  be  stacked.  As  a  general 


DREDGING   FOR  METALS 


225 


rule  the  box  is  from  40  to  50  ft.  long  and  varies  in  width  from  3  to 
6  ft.,  according  to  the  class  of  materials  to  be  treated.  The  pitch 
depends  on  the  same  thing  and  is  from  1  in  8  to  1  in  10.  Fig.  74 
shows  a  sluice-box  as  given  in  a  paper  by  Messrs.  E.  S.  and  G.  N. 
Marks,  reproduced  in  Engineering  News,  from  which  this  description 
is  condensed.  The  bottom  of  the  box  is  laid  with  perforated  plates 
and  ripples  for  its  entire  length,  the  ripples  overlying  the  fibrous 
matter.  It  was  found  convenient  to  use  as  many  different  classes 
of  ripples  as  possible  so  as  to  alter  the  flowing  of  water  and  conse- 
quently the  material  being  treated  is  tossed  about,  and  the  gold 


Plan.  | 

FIG.  74. — Placer  Dredge  with  Sluice-box. 

which  may  be  adhering  to  the  stones  has  more  chance  of  being 
liberated.  The  classes  of  ripples  used  are  angle  iron,  Venetians, 
perforated  plates  and  crimped  or  diamond-shaped.  A  return  box 
is  sometimes  used  fitted  as  indicated  in  the  figure.  An  opening  is 
made  at  the  bottom  of  the  box  over  which  a  perforated  plate  is 
placed  and  all  the  material  that  passes  under  the  plate  goes  out  by 
the  return  box  behind  the  tail  of  the  sluice  run.  The  return  box 
serves  two  purposes:  it  either  saves  any  light  gold  that  has  traveled 
down  the  sluice-box  or  else  it  may  be  used  to  prevent  a  portion  of 
the  water  from  falling  on  the  tailings.  Plan  and  elevation  of  a 
ladder  dredge  with  long  sluice-box  as  used  in  Australia  is  given  in 
Fig.  75,  reproduced  from  the  paper  of  Messrs.  Marks. 


226 


A  TREATISE  ON  DREDGES   AND   DREDGING 


The  stones,  gravel  and  in  general  the  residual  materials  left 
after  being  washed  out  in  the  screens  are  expelled  from  the  dredge 
and  deposited  in  places  where  they  will  not  interfere  any  more 
with  the  dredging  operations.  For  this  purpose  different  appliances 
are  used.  Thus  for  instance  in  the  type  of  dredge  with  revolving 
screen  illustrated  in  Fig.  74  the  materials  coming  out  from  the 
lower  end  of  the  revolving  screen  enter  into  a  chute,  which  is  high 
enough  and  sufficiently  inclined  to  discharge  them  clear  of  the 
sides  of  the  boat.  This  method  is  convenient  when  dredging  is 
made  by  scraping  the  soil  on  parallel  lines  and  depositing  the 
washed  materials  always  on  the  same  side  of  the  dredge  and  above 


FIG.  75. — Plan  and  Elevation  of  a  Long  Sluice-box. 

the  ground  already  treated.  But  the  most  common  method  of 
disposing  of  the  washed  materials  is  by  means  of  the  elevator  or 
tailing  stacker  as  indicated  in  the  Fig.  75.  This  consists  of  an 
inclined  steel  trussed  beam  with  its  lower  end  hinged  to  the  stern 
of  the  pontoon  while  its  upper  end  is  supported  by  a  gantry.  Ropes 
and  pulleys  allow  the  adjusting  of  this  beam  to  such  heights  as 
are  required  for  the  stacking  of  the  materials.  The  upper  side  of 
the  beam,  is  provided  with  roller  supporting  the  endless  rubber 
belt,  thus  forming  a  proper  belt  conveyor  of  the  usual  type,  the 
belt  being  moved  along  by  the  driving  drum  located  at  the  lower 
end  of  the  beam  and  geared  to  a  special  engine.  The  materials  from 
the  screens  are  conveyed  through  a  chute  made  of  steel  plates,  over 


DREDGING  FOR  METALS  227 

• 

the  belt,  along  which  they  travel  and  are  tipped  over  when  the  belt 
revolves  around  the  guiding  drum  at  the  upper  end  of  the  beam. 
Provisions  arc  made  to  prevent  the  tipping  of  the  materials  on  the 
sides  at  the  beam.  The  beam  is  made  50  or  60  ft.  long,  thus  allowing 
the  dumping  of  the  material  at  some  distance  from  the  back  of  the 
dredge. 

These  ladder  dredges  may  be  operated  either  by  steam  engines 
or  by  electric  motors.  Where  two  or  more  dredges  are  in  close 
proximity  to  each  other  it  is  more  economical  to  locate  a  power 
station  on  shore  and  transmit  electricity  to  the  dredges  than  to  have 
engines  or  boilers  on  board. 

These  dredges  as  a  rule  do  not  work  in  rivers,  but  in  trenches 
contiguous  thereto.  In  most  cases  a  pit  is  dug  deep  enough  for  the 
dredge  to  float  in  and  of  sufficient  dimensions  to  allow  it  to  turn 
round.  Very  little  water  is  required  to  float  the  dredge  and  to 
operate  it,  as  the  water  which  is  pumped  for  washing  purposes 
comes  back  to  the  pit.  The  amount  of  water  is  determined  by 
seepage  and  the  cleanness  of  the  gravel  dug.  The  face  of  the  pit 
must  be  kept  square  and  its  corners  worked  up,  otherwise  it  will 
gradually  narrow  and  ground  will  be  left. behind  and  lost.  The 
dredge  works  ahead,  undermining  the  banks,  and  the  material  will 
naturally  fall  to  the  buckets,  when  good  work  will  result,  and  the 
dredge  can  then  run  for  an  hour  or  more  with  full  buckets  without 
being  moved. 

It  is  very  important  to  keep  the  dredge  running  as  near  24  hours 
a  day  as  possible,  for  when  a  dredge  stops,  the  producing  part  of 
the  plant  stops,  while  the  expenses  continue.  Well-managed  dredges 
are  making  a  monthly  average  of  from  80  to  90  per  cent  of  the 
possible  running  time,  including  that  lost  for  cleaning  up  of  the  gold 
tables,  an  operation  which  takes  from  5  to  6  hours  every  fifteen 
days.  This  time,  however,  is  not  all  dead  loss,  as  it  can  be  used  to 
advantage  in  general  repairs. 

Of  Australian  dredges  Messrs.  Marks  say:  "The  sluice-box  or 
tables  are  cleaned  up  weekly,  and  the  clean-up  is  conducted  as 
follows:  In  either  case  the  ripples  or  pieces  of  expanded  metal 
are  lifted  and  the  lighter  material  caught  in  the  sluice-box  or  tables, 
is  run  off  the  mats  by  a  gentle  stream  of  water,  the  gold,  heavy 
sands,  and  pieces  of  metal  of  any  description  alone  remaining. 
The  mats  being  run  clear,  the  water  is  turned  off,  and  the  calicoes 
(which  are  forming  the  upper  stratum  of  the  mattress  of  fibrous 


228 


A  TREATISE   ON  DREDGES   AND   DREDGING 


matter)  are  lifted  and  washed  one  by  one  into  a  gold-box  or  tub 
until  quite  clean.  When  all  the  mats  have  been  washed,  they 
are  relaid  as  before,  preparatory  to  starting  work. 

The  action  of  the  buckets  is  slow  but  gradual.  In  the  close- 
connected  type  the  number  per  minute  ranges  from  18  to  30, 
while  with  link  type  12  to  14  are  delivered.  The  speed  of  the 
ladder  is  generally  about  50  ft.  per  minute,  varying  with  the  hard- 
ness of  the  ground.  Sometimes  it  is  reduced  to  less  than  40  ft., 
and  again  is  increased  to  75  ft.  These  dredges  are  now  built  to 


FIG.  76.— Placer  Dredge. 

excavate  to  a  depth  of  65  ft.    Fig.  76  illustrates  this  type  of  dredge. 

The  following  description  of  the  "Hunter  Dredge"  and  of  its 
work,  and  the  cost  of  excavating  gravel  with  it,  is  condensed  from 
an  article  in  Engineering  Contracting: 

"This  dredge  was  built  by  the  Western  Engineering  and  Construc- 
tion Co.,  of  San  Francisco,  Cal.,  for  the  Oro  Water,  Light  and  Power 
Co.,  of  Oroville,  Cal.  The  dredging  machinery  proper  was  manu- 
factured by  the  Bucyrus  Co.  of  South  Milwaukee,  Wis.  Operation 
of  the  dredge  was  commenced  in  August,  1907,  working  placer 
gravel  38  ft.  deep  from  the  water  line  to  bed  rock. 

"The  entire  plant  embodies  the  latest  type  of  construction, 


DREDGING  FOR  METALS  229 

• 

the  hull  being  especially  trussed  along  the  well-hole  line  with  an 
overhead  structure.  The  bow  gantry,  supporting  the  digging  ladder 
and  buckets,  is  of  the  most  improved  design,  being  constructed 
to  minimize  working  of  the  low  pontoons. 

"  The  buckets,  each  of  5  cu.ft.  capacity,  are  close  connected,  and 
are  provided  with  heavy  manganese  steel  lips.  Altogether  there 
are  82  buckets. 

"There  are  two  winches  on  the  boat,  both  located  forward; 
one  on  the  port  side,  by  means  of  which  the  digging  ladder  is  raised 
and  lowered;  the  other  on  the  starboard  side,  carrying  the  auxiliary 
lines  used  in  swinging  the  dredge  from  side  to  side.  The  digging 
ladder  is  held  up  hard  and  fast  to  the  face  of  the  cut  by  means  of 
a  steel  spud  24  by  36  in.  and  50  ft.  long.  A  wooden  spud  is  also 
provided,  of  the  same  dimensions  as  the  steel  spud,  and  is  chiefly 
used  to  move  the  dredge  forward  after  the  bed  rock  has  been  cleaned 
and  a  new  cut  is  necessary.  In  this  process,  both  spuds  are  alter- 
nately raised  and  lowered,  until  the  dredge  has  stepped  ahead  to 
the  position. 

"This  machine  is  operated  entirely  by  electricity.  Electric 
•  power  is  delivered  at  the  dredge  at  approximately  4000  volts,  being 
carried  aboard  by  armored  cable  at  that  voltage  and  stepped 
down  with  transformers  from  4000  volts  to  400.  The  following 
motor  equipment  is  used:  The  digging  motor  is  a  100  H.P.  type  F, 
variable  speed,  operating,  as  all  motors  do,  at  400  volts,  and  having 
a  speed  of  600  R.P.M.  It  is  connected  by  belt  to  the  port  winch, 
which  drives  the  bucket  line,  and  lowers  or  raises  the  ladder. 

"The  motor  connected  with  the  starboard  winch  by  a  belt 
is  of  20  H.P.,  type  F,  variable  speed,  having  a  speed  of  900  R.P.M. 
By  means  of  this  motor  and  winch,  the  wooden  and  steel  spuds  are 
hoisted,  the  stacker  raised  and  lowered,  and  the  side  and  head  lines 
in  handling  the  dredge  controlled. 

"The  8-in.  centrifugal  pump  is  direct  connected  to  a  50  H.P., 
motor,  type  CCL,  constant  speed,  having  a  speed  of  850  R.P.M. 
A  15  H.P.  motor  of  the  same  type  with  a  speed  of  1120  R.P.M.  is 
direct  connected  to  the  4-in.  centrifugal  pump. 

"The  revolving  screen  with  a  speed  of  approximately  8  R.P.M. 
is  operated  by  a  belt  from  a  20  H.P.,  type  CCL,  constant  speed 
motor,  having  a  speed  of  1120  R.P.M.,  and  connected  by  belt  to 
the  drive  of  the  conveyor.  As  stated,  this  is  of  the  Robbins  type, 
equipped  with  a  30-in.  special  Diamond  Dredge  belt,  the  entire  con- 


230  A  TREATISE  ON  DREDGES  AND   DREDGING 

veyor  being  102  ft.  between  centers.  As  originally  installed  it  was 
only  90  ft.,  but  it  was  found  necessary  to  lengthen  it.  All  the 
electric  motors  were  manufactured  by  the  Westinghouse  Co. 

"When  all  drivers  are  being  used  225  H.P.  is  needed,  but  this 
seldom  occurs.  The  main  drive  motor,  which  operates  the  bucket, 
line  and  ladder  hoist,  is  in  use  nearly  all  the  time.  The  starboard 
winch  motor  is  used  more  or  less  intermittently,  only  when  it  is 
necessary  to  raise  and  lower  the  spuds,  or  the  stacker,  or  swing 
the  dredge  from  side  to  side.  The  pump  motors  are  used  constantly 
in  supplying  water  for  the  revolving  screen  and  tables,  also  for  the 
bucket  washing  apparatus,  where  the  buckets  jump  at  inversion 
at  the  upper  tumbler.  Both  revolving  screen  and  stacker  belt 
motors  are  constantly  in  use,  the  one  driving  the  revolving  screen 
or  "grizzly,"  as  it  is  commonly  termed,  for  properly  screening  the 
gravel,  the  other  in  connection  with  the  stacker  belt,  which  carries 
off  the  tailings.  The  digging  buckets  average  speed  is  about  22 
buckets  per  minute,  this  naturally  varying  according  to  the  nature 
of  the  ground. 

"From  90,000  to  110,000  K.W.  hours  are  used  per  month  on  the 
dredge,  making  a  daily  rate  of  from  3000  to  3666  K.W.  hours. 
The  cost  of  current  is  1  cent  per  K.W.  hour. 

"The  entire  cost  of  this  dredge  ready  for  operation  was  $90,000. 

"  Such  a.  dredge  is  operated  during  a  monthly  average  of  from 
80  to  90  per  cent  of  the  possible  running  time.  The  dredge  is  operated 
24  hours  per  clay,  with  the  three  8-hour  shifts.  All  stops  of  whatever 
nature  are  counted  in  the  average  time  made;  for  breakdowns  of 
machinery,  power  shutdowns,  and  for  cleaning  up.  A  clean-up 
is  made  twice  a  month  usually  taking  up  four  or  five  hours.  The 
time  is  not  lost  entirely,  as  it  is  taken  advantage  of  to  make  needed 
repairs.  To  obtain  such  running  results,  duplicates  of  all  wearing 
parts  must  be  kept  on  hand  to  be  replaced  with  the  least  possible 
delay. 

"  Such  a  dredge  is  operated  by  two  men,  one  being  a  winchman, 
the  other  an  oiler.  Many  of  the  dredges  employ  a  shoreman  to  dig 
deadmen  and  help  in  handling  the  shore  line.  In  addition  to  these 
most  of  the  dredges  carry  a  dredgemaster. 

"The  wages  paid  to  the  men  are  as  follows: 

Dredgemaster ' $150.00  per  month 

Winchman 3 . 50  per  day 

Oiler 2.50 

Shoreman..  : 2.00       " 


DREDGING  FOR  METALS  231 

"The  Hunter  dredge,  working  30  days  a  month,  excavated  106,000 
cu.yds.  of  very  hard  material  with  a  large  number  of  boulders  in  it. 
The  cost  of  this  month's  work  was  as  follows: 

LABOR: 

1  dredgemaster $150 . 00 

3  winchmen,  30  days .  310 . 00 

3  oilers,  30  days 225.00 

2  shoremen,  30  days 120.00 


Total $805.00 

POWER: 

100,000  K.W.  hours $1,000.00' 

Supplies,  etc 210.00 

PLANT: 

Interest,  depreciation,  and  repairs  (estimated) 1,800.00 


Total $3,815.00 

"This  gives  the  cost  per  cu.yd.  including  our  estimated  allowance 
for  plant  as  follows; 

Labor $0.007 

Power 0.009 

Supplies 0.002 

Plant..  0.017 


Total $0.035 

"This  shows  how  wonderfully  efficient  these  dredges  are.  It  is 
also  worthy  of  note  how  small  a  crew  operates  so  large  a  machine. 
A  company  operating  one  or  more  of  these  dredges  employs  a  black- 
smith and  helpers  to  make  repairs  and  keep  up  the  machinery, 
and  also  a  superintendent  who  gives  the  work  general  supervision 
and  is  present  at  the  semi-monthly  clean-ups. 

"It  is  found  that  large  dredges  are  more  economical  than  the 
smaller  machines,  and  to-day  the  American  practice  is  to  use  large 
capacity  dredges.  Some  of  the  latest  machines  are  equipped  with 
13  ft.  buckets.  These  are  operated  by  the  same  size  crew  as  that 
given  for  the  Hunter  dredge,  and  although  the  cost  for  power 
is  larger  and  the  charge  for  maintenance  and  depreciation  is  greater 
yet  the  total  cost  is  less.  Some  of  the  largest  machines  now  built 
have  averaged  260,000  cu.yds.  of  gravel  per  month,  while  some 
have  even  obtained  a  record  of  280,000  cu.yds.  This  would  mean 
a  charge  per  cu.yd.  for  labor  of  only  .00278  cts.,  a  very  low  cost." 

The  following  cost  data  are  extracted  from  the  Mining  and 
Scientific  Press  and  are  of  value,  as  they  cover  a  period  of  years. 


232 


A  TREATISE   ON  DREDGES  AND   DREDGING 


"The  costs  given  cover  the  operating  expenses,  the  cost  of  all 
repairs  necessary  to  keep  the  dredges  in  first-class  working  condition, 
and  the  cost  of  extraordinary  breakages  and  accidents;  all  of  which 
latter  are  properly  included  in  dredging  costs.  Estimates  of  costs 
which  do  not  include  the  last-mentioned  items  are  to  that  extent 
fictitious. 

1..  "A  dredge  having  3^  cu.ft.  buckets,  digging  in  ordinarily 
loose  gravel  and  sand. 

OPERATING   COSTS   IN  CENTS   PER   CUBIC   YARD 


Years. 

Average 
for  6 
Years. 

1 

2 

3 

4 

5 

6 

Labor     

2.913 

1.886 

3.133 
1.960 
0.180 
3.383 
0.658 

3.975 
2.467 
0.255 
2.624 
0.797 

.2.687 
1.542 
0.194 
2.515 
0.672 

3.011 
1.446 
0.211 
2.395 
1.354 

2.853 
1.487 
0.195 
1.717 
1.077 

2.877 
1.655 
0.154 
2.480 
0.825 

Power  

Water 

Repairs  and  supplies 
General  expense  .... 

Total 

2.415 
0.745 

7.959 

9.314 

10.118 

7.610 

8.417 

7.329 

7.991 

2.  "A  5  cu.  ft.  dredge,  working  in  tight  gravel  and  clay.    The 
material  should  properly  be  considered  as  tough  rather  than  hard. 

OPERATING  COSTS   IN  CENTS   PER  CUBIC  YARD 


Years. 

Average 
for  4 
Years. 

1 

2 

3 

4 

Labor 

3.814 
1.912 
0.340 
2.709 
1.260 

4.069 
1.815 
0.323 

2.788 
0.959 

3.356 
1.622 
0.374 
4.297 
1.124 

3.060 
1.425 
0.292 
3.062 
1.145 

3.557 
1.687 
0.333 
3.246 
1.124 

Power        '.  . 

Water  

Repairs  and  supplies  

General  expense 

Total  

10.035 

9.954 

10.773 

8.984 

9.947 

"  Dredge  No.  2,  working  in  such  ground  as  is  No.  1,  would  operate 
at  a  total  cost  of  about  5.59  cents/' 


CHAPTER    XXVI 

DREDGING     FOR     INDUSTRIAL     PURPOSES— SAND     DREDGING— 
DREDGING   FOR  FILLING   UP   LOW  LAND 

• 

Sand  Dredging  for  Commercial  Purposes.  Another  industry 
based  exclusively  upon  the  work  of  dredges  is  the  excavation  of 
sand  and  gravel  from  the  great  rivers  for  commercial  purposes. 
This  industry  was  described  by  Mr.  Richard  G.  Donovan  in  an 
interesting  article  contributed  to  the  Engineering  Record,  Jan.  5, 
1906,  which  is  slightly  condensed  here. 

One  of  the  important  industries  on  the  Mississippi  River  and 
its  tributaries  is  dredging  sand  and  gravel  for  commercial  purposes. 
These  rivers  carry  an  immense  volume  of  sand,  gravel  and  other 
matter  which  form  large  bars  at  locations  where  the  current  is 
checked.  The  annual  floods  also  play  an  important  part  in  the 
formation  of  these  bars,  for  the  high  velocity  of  the  river  during 
these  periods  tends  to  erode  the  bed  and  side  banks;  when  the 
floods  decline  the  load  is  too  heavy  for  the  decreasing  velocity, 
and  the  gravel  and  sand  are  rapidly  deposited. 

In  the  Ohio  River  at  some  localities  gravel  is  found  in  large 
quantities  with  but  a  small  percentage  of  sand,  while  in  other 
places  the  bars  may  be  entirely  of  sand.  In  the  Pittsburg  district 
the  Allegheny  River  is  noted  for  its  fine  clean  sand,  and  most  of 
the  sand  used  in  the  district  comes  from  this  river.  The  sand  from 
the  Monongahela  River,  on  the  other  hand,  is  dirty  and  contains 
injurious  deposits  from  the  numerous  manufacturing  plants  along 
its  banks.  In  the  Mississippi  River,  as  a  rule,  the  bars  contain 
fine,  fairly  clean  sand  of  quite  recent  deposits.  An  immense  amount 
of  sand  and  gravel  is  taken  from  the  rivers  annually  and  the  develop- 
ment of  this  business  has  resulted  in  the  adoption  of  certain  types 
of  dredges  to  meet  the  peculiar  conditions  existing  in  the  various 
localities.  Those  more  commonly  employed  are  the  hydraulic, 
the  ladder  and  the  grab-bucket  dredges. 

233 


234  A  TREATISE   ON   DREDGES  AND   DREDGING 

The  Hydraulic  Dredge.  The  hydraulic  dredge  has  been  used 
extensively  in  removing  sand-bars  along  the  Mississippi  River,  and 
the  private  concerns  engaged  in  dredging  sand  for  commercial 
purposes  have  found  these  machines  efficient. 

The  hull  consists  of  a  scow  of  the  light-draft  square  type,  of 
heavy  construction,  being,  as  a  rule,  housed  over  and  arranged 
with  suitable  quarters  for  the  crew.  The  dredging  end  of  the  hull 
is  provided  with  a  strong  A  frame  to  support  the  suction  head, 
which  projects  beyond  the  hull.  The  other  end  is  provided  with 
means  for  the  proper  handling  and  anchorage  of  the  dredge.  The 
dredging  end  is  usually  downstream — see  Fig.  77. 

The  pump  used  is  of  the  centrifugal  type  with  a  runner  provided 
with  four  curved  blades.  The  runner  is  closely  fitted  to  the  casing, 
and  this  is  necessary  in  order  that  the  discharge  may  not  leak  back 
into  the  suction.  In  the  operation  of  the  pump  in  sand  or  gravel 
dredging,  the  question  of  wear  is  an  important  one,  and  in  the 
latest  designs  the  runners  are  of  steel  and  large  space  is  provided 
in  the  discharge  volute.  Of  course  no  sharp  bends  should  be 
allowed  and  the  passages  in  the  pump  should  be  larger  than  the 
Buction  pipe  so  as  to  prevent  obstruction  by  stones. 

In  many  dredges  special  arrangements  are  provided  for  stirring 
up  or  agitating  the  sand  at  the  suction  end.  This  is  usually  accom- 
plished by  directing  strong  jets  of  water  into  the  sand,  resulting  in 
the  upheaval  of  the  latter,  which  is  caught  up  by  the  suction  and 
drawn  into  the  suction  pipe.  The  discharge  from  the  pump  is 
arranged  so  that  the  barge  moored  on  the  side  of  the  dredge  may 
be  conveniently  filled.  An  open  discharge  trough  with  screen  of 
any  desired  mesh  in  the  bottom  is  suspended  over  the  barge  so  that 
any  stones  or  coarse  gravel  may  be  washed  past  and  discharged 
overboard.  The  operator  whose  duty  is  to  feed  the  suction  head 
in  the  sand  is  situated  so  that  he  can  see  the  barge  and  regulate 
the  depth  of  the  suction  head  by  observing  the  discharge 
mixture. 

The  centrifugal  pump  is  usually  driven  by  a  compound  steam 
engine,  of  either  the  vertical  or  horizontal  type.  As  a  rule,  the 
dredges  operated  by  the  larger  companies  have  a  double  equipment, 
consisting  of  a  pump  on  each  side,  so  that  barges  may  be  loaded 
on  both  sides.  A  powerful  hoisting  engine  is  provided  for  raising 
the  suction  head,  and  steam  power  is  applied  to  the  capstans  and 
other  handling  machinery.  As  a  rule  the  Mississippi  River  type 


23'6 


A  TREATISE   ON  DREDGES   AND   DREDGING 


of  boiler  is  used,  and  all  these  commercial  dredges  are  of  the  non- 
propelling  type. 

The  Ladder  Dredge.  For  the  excavation  of  gravel  in  the  upper 
Ohio  and  Allegheny  Rivers  the  hydraulic  dredges  are  not  found 
suitable  owing  to  the  fact  that  the  material  will  not  readily  flow 
into  the  end  of  the  suction  pipe  and  the  wear  on  the  pump  and  other 
parts  of  the  machine  would  be  simply  enormous.  For  such  work 
the  ladder  or  elevator  type  of  dredge  is  well  adapted,  and  in  fact, 
almost  all  the  dredges  operated  by  the  sand  companies  in  the  upper 
Ohio  and  Pittsburg  districts  are  of  this  type.  Fig.  78. 

The  hull  used  in  this  type  of  dredge  is  of  the  usual  square  barge 
construction.  It  is  built  of  wood  with  heavy  timber  frames, 
thus  securing  great  strength  and  stiffness.  The  dredging  apparatus 


FIG.  78. — Ladder  Sand  Dredge. 

is  usually  arranged  on  the  side,  since  this  results  in  cheap  construc- 
tion, and  allows  a  more  compact  arrangement  of  machinery.  The 
hull  is  housed  over  and  frequently  quarters  are  provided  for  the 
crew.  Some  of  the  dredges  are  self-propelling,  the  dredging 
apparatus  being  fitted  on  the  side  of  a  stern-wheel  river  steamboat. 

The  ladder  is  of  very  strong  construction;  as  a  rule,  it  is  of  timber 
with  steel  bracing.  The  members  forming  the  ladder  are  connected 
by  bracing,  and  at  their  upper  end  by  a  shaft  which  is  carried  in  a 
frame  forming  part  of  the  hull,  so  as  to  permit  the  ladder  to  revolve 
and  change,  the  position  of  the  lower  end. 

The  top  tumbler  construction  is  of  great  strength,  as  it  is  here 
that  the  power  is  applied  to  the  conveyor  system  and  the  cutting 
resistance  overcome.  The  buckets  forming  the  conveyor  system 
are  usually  of  steel  plates  riveted  together  by  a  chain  formed  of 


DREDGING  FOR  INDUSTRIAL  PURPOSES  237 

steel  bar  links  pinned  at  their  ends  so  as  to  allow  them  to  work 
around  the  tumblers.  Roller  bearings  are  fitted  along  the  ladder 
at  intervals  to  insure  uniform  support  to  the  train  of  loaded 
buckets.  The  material  is  cut  out  and  carried  up  the  ladder  and 
dumped  at  the  top  tumbler.  The  empty  buckets  are  returned 
toward  the  bottom  without  support  so  that  the  empty  train  in 
motion  hangs  suspended  between  the  top  and  bottom  tumblers. 
The  sand  and  gravel  are  separated  by  a  moving  screen,  which  is 
so  arranged  that  the  coarse  gravel  may  be  loaded  on  one  side  of 
the  dredge  and  sand  on  the  other. 

The  machinery  used  in  the  non-propelling  type  of  dredge 
usually  consists  of  boiler  and  engine  equipment  of  sufficient  power 
to  operate  the  conveyor  system  and  provide  power  for  capstans, 
syphons,  etc.  The  transmission  of  power  to  the  ladder  is  generally 
made  through  chain  gears  and  the  raising  and  lowering  of  the  dredg- 
ing end  of  the  ladder  is  performed  by  a  lifting  device  operated  by 
power  from  the  main  engine.  Steam  capstans  are  provided  for 
handling  the  barges  and  for  changing  location  by  using  the  mooring 
lines.  In  the  propelling  type  of  ladder  dredge  the  boiler  equipment 
must  be  of  sufficient  capacity  to  operate  both  the  dredging  and 
propelling  machinery.  The  latter  consists  of  the  usual  stern  wheel 
equipment,  which  of  course  is  entirely  independent  of  the  dredging 
apparatus. 

The  Grab-bucket  Dredge.  The  use  of  the  grab  bucket  or  clam- 
shell in  sand  dredging  for  commercial  purposes  is  very  limited.  This 
type  in  the  relatively  shallow  rivers  cannot  be  operated  as  econom- 
ically as  the  other  types  discussed,  since  its  speed  is  much  lower  and 
the  nature  of  its  operation  necessitates  elaborate  details  for  the 
screening  of  the  sand  or  gravel.  However,  as  illustrating  a  novel 
method  of  using  the  grab  bucket,  attention  is  called  to  the  figure 
showing  such  an  apparatus  for  digging  gravel  direct  from  the  river 
bed.  The  apparatus  travels  along  the  broad  gauge  track  on  the 
river  bank  and  the  cars  to  be  loaded- are  run  under  the  machine.  The 
grab  bucket  travels  out  on  the  overhanging  arm,  and  on  being  filled 
is  carried  back  and  the  gravel  dropped  into  the  cars. 

Method  of  Handling  Sand.  In  transporting  the  sand  or  gravel, 
from  the  dredge  to  the  unloading  station,  two  types  of  carriers 
are  used,  the  decked  barges  and  the  open-hold  barge.  In  the  Missis- 
sippi River  sand  business  with  the  centrifugal  dredge,  the  decked 
type  is  exclusively  used,  while  in  the  upper  Ohio  district  where 


238  A  TREATISE  ON  DREDGES  AND   DREDGING 

the  elevator  or  ladder  dredge  is  used  the  open-hold  barge  is  the 
standard  type. 

For  the  efficient  operation  of  the  centrifugal  pump  it  is  necessary 
that  there  be  a  large  percentage  of  water  in  the  sand.  On  the  other 
hand,  it  is  necessary  for  the  economical  handling  of  the  sand  that 
it  be  as  free  from  water  as  possible.  The  decked  barge  with  cargo 
box  has  been  designed  to  meet  these  conditions.  The  cargo  box  is 
formed  by  fitting  sideboards  about  3  ft.  .high  and  arranging  hopper 
ends,  inclosing  nearly  all  the  deck  area,  leaving  but  a  small  space 
at  each  end  for  handling  lines.  The  barge  is  placed  alongside  the 
dredge  and  the  mixture  of  sand  and  water  from  the  centrifugal 
pump  is  directed  into  the  inclosed  deck  space. 

These  decked  barges  are  subject  to  very  severe  usage  in  the 
operations  of  handling  and  unloading.  The  large  sand  companies 
operating  on  the  Mississippi  River  have  installed  unloading  machinery 
of  the  largest  capacity  with  corresponding  weight  of  parts.  The 
immense  grab  buckets  come  down  on  the  deck  with  considerable 
shock,  causing  heavy  local  stresses,  so  that  the  deck  supports  must 
be  close  together  and  of  ample  section.  In  unloading,  it  is  also 
necessary  at  times  to  take  out  the  sand  very  unevenly,  such  as 
removing  it  from  one  end  only,  or  from  the  middle,  giving  rise  to 
heavy  longitudinal  bending  stresses,  which  must  be  provided  for 
by  continuous  longitudinal  bulkheads.  This  service  tells  heavily  on 
the  wooden  barge,  and  its  upkeep  is  a  matter  of  considerable  expense 
and  ultimate  renewal  after  a  comparatively  short  life. 

With  the  increasing  use  of  steel  for  river-boat  construction, 
several  steel-decked  barges  have  been  placed  in  service  by  one 
of  the  largest  sand  companies  on  the  Mississippi  River.  These 
barges  are  130  ft.  long,  30  ft.  wide  and  7J  ft.  deep.  A  complete 
steel  deck  is  fitted,  and  on  this  a  wood  box  is  arranged  by  fitting 
timber  sideboards  3  ft.  high.  The  deck  beams  are  framed  longi- 
tudinally so  as  to  better  care  for  the  impact  of  the  grab  bucket, 
which  is  used  with  its  cutting  edges  across  the  barge.  Longitudinal 
strength  is  secured  by  a  system  of  lattice  girders  carried  full  length, 
while  the  transverse  strength  is  provided  for  by  a  system  of  cross 
trusses.  The  deck  beams  are  supported  at  close  intervals  by  the 
cross  trusses,  and  by  extra  cross  beams  carried  by  the  side  frames. 
Channel  sections  are  used  to  a  large  extent  in  the  framing,  which 
is  spaced  rather  closely  throughout  the  barge  to  insure  strength  and 
stiffness. 


DREDGING  FOR  INDUSTRIAL  PURPOSES  239 

• 

These  barges  have  a  capacity  of  about  400  cu.yds.  of  sand 
and  draw  about  6  ft.  9  in.  in  the  loaded  condition.  They  have 
demonstrated  their  ability  to  withstand  the  severe  service  and 
are  much  more  economical  in  operation  than  the  wooden  type. 
Of  course  the  steel  construction  costs  considerably  more  than  the 
wood,  but  when  depreciation,  cost  of  upkeep,  and  interest  on  invest- 
ment are  considered,  it  will  be  seen  that  the  steel  barge,  with  its 
life  triple  that  of  the  wood,  is  the  better  business  proposition. 

In  elevator  or  ladder  dredging,  the  open-hold  barge  is  used  to 
receive  the  sand  or  gravel.  From  the  nature  of  this  dredging, 
practically  no  free  water  is  carried  into  the  barge,  and  it  is  only 
necessary  to  provide  a  suitable  open  carrier.  As  a  rule,  these  barges 
do  not  have  to  meet  the  severe  conditions  incidental  to  Mississippi 
River  dredging.  The  distance  they  are  towed  is  usually  much 
less  and  the  unloading  machinery  is  not  of  such  heavy  type.  The 
barges,  however,  are  of  substantial  construction  and  are  well  adapted 
to  the  service.  The  common  carrier  used  in  the  Pittsburg  district 
is  about  100  ft.  long,  24  ft.  in  beam,  and  has  a  depth  of  8  ft.,  and  a 
capacity  of  about  175  yds. 

Unloading  Machinery.  The  usual  arrangements  provided  for 
the  reception  of  the  sand  from  the  barge  consist  of  elevated  bins 
situated  conveniently  on  the  river  bank  in  connection  with  some 
type  of  unloading  device.  These  bins  are  usually  so  arranged  that 
cars  or  other  means  of  conveyance  may  be  loaded  readily.  In  the 
type  of  unloader  much  diversity  exists,  but  the  illustrations  show 
some  of  the  most  modern  Mississippi  River  stations  with  their 
machinery.  These  structures  are  of  steel.  Steam  and  electric 
power  are  used,  and  manual  labor  is  reduced  to  the  minimum. 
In  unloading  the  barges,  no  attempt  is  made  to  clean  out  the  cargo 
box  beyond  the  action  of  the  grab  bucket.  These  buckets  are  very 
heavy  and  at  times  much  injury  is  done  the  deck  by  allowing  them 
to  descend  too  rapidly.  The  capacities  of  the  buckets  vary  from 
2  to  4  yds.  and  the  speed  in  operation  from  75  to  150  yds.  per  hour. 
At  some  of  these  plants  the  sand  or  gravel  is  carefully  screened 
into  different  grades  for  various  purposes.  In  the  upper  Ohio  district 
the  unloading  stations  are  not  built  on  such  a  large  scale  and  the 
unloading  machinery  is  not  of  such  large  capacity  nor  of  such  elaborate 
parts.  Some  of  the  unloaders  consist  of  a  boom  derrick  and  bucket 
which  is  swung  into  the  barge  and  filled  by  hand,  while  others  consist 
of  a  medium-size  grab  bucket  operated  by  boom  derrick.  Storage 


240 


A  TREATISE  ON  DREDGES  AND   DREDGING 


bins  are  seldom  used,  and  in  many  cases  the  bucket  loads  are  dumped 
directly  into  wagons  or  cars,  or  else  the  sand  is  piled  along  the  bank. 

Fig.  79  illustrates  some  of  the  machines  for  unloading  barges 
along  the  Mississippi  River. 

Filling  Marsh  Lands.  The  transportation  of  the  excavated 
materials  to  the  dumping  place  is  one  of  the  most  expensive  items 
of  dredging.  Engineers  have  devised  schemes,  not  only  for  eliminat- 
ing this  item  of  expense,  but  if  possible  to  obtain  some  benefit  from 
this  bulky  and  otherwise  useless  material.  Small  drainage  canals 
have  sometimes  been  excavated  at  a  very  low  cost  owing  to  the 


FIG.  79. — Machine  for  Unloading  Sand  from  Barges. 


fact  that  the  debris  was  deposited  directly  alongside  the  cut,  thus 
entirely  eliminating  their  transportation.  Some  harbor  and  river 
improvements  have  also  been  made  at  a  comparatively  small  cost 
on  account  of  using  the  dredged  materials  for  filling  up  lowlands 
located  along  the  water  front.  In  a  few  instances  dredging  operations 
have  been  made  profitable  by  reclaiming  either  for  agricultural 
or  industrial  purposes  some  marshy  lands  which  were  not  only 
valueless,  but  dangerous  to  the  health  of  the  surrounding  population 
as  breeding  places  for  mosquitoes.  But  in  these  particular  cases 
the  filling  up  of  lowlands  was  of  a  secondary  importance. 

It  is  only  recently  that  dredging  has  been  undertaken  for  the 


DREDGING   FOR   INDUSTRIAL  PURPOSES 


241 


exclusive  purpose  of  reclaiming  low  and  marshy  lands  in  localities 
near  large  cities.  In  these  cases  hydraulic  dredges  are  employed 
to  excavate  the  materials  from  the  bottom,  raise  them  to  the 
surface  and  convey  them  to  the  lands  to  be  filled  by  means  of  long 
lines  of  pipes.  Thus  in  the  year  1885  the  dredge  "Badger"  was 
used  at  Coney  Island,  N.  Y.,  to  fill  up  some  lowlands  which  were 
sold  at  a  high  price  for  amusement  and  residence  purposes. 

In  the  Engineering  News,  June  13,  1901,  was  given  a  description 
of  filling  up  tide-water  flats  at  Seattle,  Wash.,  which  is  given  here 
in  a  condensed  form. 

The  city  of  Seattle,  Wash.,  is  built  upon  the  hills  lying 
between  Puget  Sound  and  Lake  Washington,  there  being  very  little 


FIG.  80. — Tide  Lands  at  Seattle. 


flat  ground  for  manufacturing  purposes.  Between  the  city  proper 
and  the  suburb  of  West  Seattle  is  a  large  area,  a  portion  of  Elliott 
Bay  which  is  overflowed  at  high  tide,  but  which  is  entirely  bare 
at  extreme  low  tide;  the  variation  from  mean  low  water  to 
extreme  high  tide,  being  16.7  ft.  These  tide  flats  have  been  filled 
with  material  taken  from  two  waterways  as  indicated  in  Fig.  80, 
each  one  1000  ft.  wide  and  30  ft.  deep  at  low  water.  These  water- 
ways connect  toward  the  South  with  Duwamish  River  and  w;th 
a  third  waterway  running  east  from  the  southern  end  of  the  east 
waterway  to  the  foot  of  the  hill,  where  it  connects  with  the  pro- 
jected ship  canal  which  is  to  be  140  ft.  wide  and  30  ft.  deep  to  Lake 
Washington.  The  difference  in  level  between  low  water  at  the 


242  A  TREATISE   ON  DREDGES  AXD   DREDGING 

lake  and  high  tide  in  the  bay  is  to  be  overcome  by  a  lock  at  the 
western  end  of  the  highland  section. 

The  general  plan  of  operation  is  to  construct  bulkheads  along 
the  margin  of  the  waterways  and  fill  in  limited  areas  behind 
it  by  hydraulic  dredges,  thus  creating  impregnable  restraining 
works,  and  inclosing  vast  interior  settling  basins  to  be  filled  with 
material  from  the  highland  section.  Contracts  have  been  made, 
so  that  when  the  construction  of  the  bulkheads  with  their  backing 
has  progressed  to  a  sufficient  extent,  work  will  be  begun  on  the 
highland  section,  by  installing  powerful  machinery  for  loosening 
the  material  by  water  under  high  pressure,  and  transporting  it 
by  the  water  in  flumes  and  pipes,  to  the  embankment  on  the  tide 
flats.  Material  from  the  highest  parts  of  the  hill  will  be  carried 
to  the  remotest  districts,  and  the  districts  near  by  will  be  filled  from 
the  lower  levels,  so  as  to  make  use  of  gravity  for  transportation. 

The  average  cost  of  filling  these  tide  lands  with  solid  materials 
is  much  less  than  the  average  cost  of  the  perishable  structures  of 
wood  and  piles  now  used  to  sustain  frame  houses  over  the  water. 
The  land  created  in  this  way  will  furnish  hundreds  of  acres  of  building 
sites,  which  will  be  traversed  by  railways,  and  abut  upon  deep 
water,  thus  affording  a  manufacturing  district  which  will  not  be 
excelled  by  any  city  of  the  United  States. 

A  remarkable  feature  of  this  enterprise  is  that  these  gigantic 
and  beneficial  works  will  be  accomplished  without  any  tax  on  existing 
properties.  The  values  that  are  to  sustain  the  charge  are  created 
by  the  operation  that  changes  the  bottom  of  the  bay,  which  as 
such  is  worthless,  into  dry  land,  and  adds,  out  of  nothing,  to  the 
taxable  values  of  the  city,  in  a  ratio  of  three  to  one  of  the  cost  of 
the  improvement. 

The  work  was  carried  on  by  the  Seattle  &  Lake  Washington 
Waterway  Co.,  with  Mr.  Eugene  Semple  as  president,  who  made 
a  contract  for  the  execution  of  the  work  with  the  Puget  Sound  Bridge 
&  Dredging  Co.  of  Seattle,  WTash. 

Dredging  for  the  sole  purpose  of  filling  up  valuable  lands  has 
been,  in  the  last  few  years,  undertaken  in  many  places,  but  chiefly 
in  the  neighborhood  of  New  York.  The  increased  valuation  of 
lands  surrounding  the  largest  cities,  owing  to  the  great  facility 
of  transportation,  has  invited  speculators  to  create  new  towns  and 
villages,  and  many  old-time  farms  have  been  cut  up  and  sold  in 
building  lots.  The  boldest  of  all  these  speculations  is  the  construe- 


DREDGING  FOR  INDUSTRIAL  PURPOSES  243 

tion  of  an  entire  new  city  along  the  shores  of  the  Atlantic  Ocean 
and  within  easy  reach  of  the  cities  of  New  York  and  Brooklyn. 
It  will  be  a  new  summer  resort  to  rival  Atlantic  City,  and  yet  at  a 
commutation  distance  from  New  York,  so  as  to  be  used  also  for 
residential  purposes  all  year  around.  The  new  city  is  located  on 
Long  Beach,  Long  Island.  The  lowlands  which  surround  Long 
Beach  have  been  filled  up  with  sand  removed  from  the  shallow 
bottom  of  the  ocean  by  two  hydraulic  dredges,  and  the  material 
conveyed  through  a  long  line  of  pipes.  The  dredges  have  dug  also 
a  navigable  channel  between  the  ocean  and  the  large  body  of  water 
existing  between  the  mainland  and  Long  Beach,  thus  permitting 
large  vessels  to  enter  and  approach  the  surrounding  lands,  which 
will  be  improved  for  industrial  purposes.  Considering  the  selling 
prices  of  the  building  lots  the  dredging  is  certainly  remunerative. 

Similar  work  to  this  in  an  extensive  manner  has  been  done 
at  Cape  May,  N.  J. 

Still  another  example  of  undertaking  dredging  operations  for 
the  exclusive  purpose  of  forming  new  lands,  is  at  Governor's  Island, 
the  headquarters  of  the  Department  of  the  East  of  the  United  States 
Army.  Governor's  Island  being  a  comparatively  small  island  just 
south  of  New  York  city  and  occupied  by  the  various  buildings 
for  offices,  officers'  residences  and  barracks,  there  is  no  room  for 
a  parade  ground,  where  the  garrison  can  be  drilled,  reviewed,  etc. 
Adjoining  islands  are  already  taken  up  for  various  purposes  and  are 
crowded  with  costly  and  important  buildings.  Hence  it  was  decided 
to  extend  Governor's  Island.  Strong  masonry  bulkhead  walls  on 
the  eastern  and  western  sides  were  built  and  extend  for  nearly 
half  a  mile  in  a  southern  direction,  with  another  bulkhead  wall 
built  across  the  two,  thus  forming  a  rectangle  of  nearly  one-half 
mile  long  by  one-half  mile  wide.  This  southern  bulkhead  wall  had 
a  gap  left  in  the  center  to  be  closed  afterward.  Two  hydraulic 
dredges  are  employed  to  deepen  the  bottom  around  the  island  and 
deposit  the  dredged  material  between  the  new  bulkheads.  Thus 
the  harbor  will  be  deepened  at  the  same  time  new  land  is  formed. 

In  this  connection  it  has  been  suggested  by  one  of  the  engineers 
of  the  Dock  Department  of  New  York  city,  that  the  city  build 
a  bulkhead  so  as  to  take  in  the  entire  area  of  water  between  the 
Battery  and  Governor's  Island  and  also  to  a  point  south  of  the 
island  for  some  distance,  and  by  means  of  dredges  reclaim  this 
large  area  for  city  purposes.  The  docks  alone  gained  in  this  manner 


244  A  TREATISE  ON  DREDGES   AND   DREDGING 

would  be  of  great  value  to  the  city,  while  many  city  blocks  would 
be  regained  for  the  city  to  sell,  besides  space  for  park  and  pleasure 
places.  It  is  also  stated  that  land  could  thus  be  obtained  for  the 
center  pier  of  a  large  suspension  bridge  to  run  from  Jersey  City  to 
Brooklyn.  Such  a  proposal  seems  visionary,  but  the  work  already 
done  at  Governor's  Island  is  a  part  of  this  scheme,  and  with  New 
York  city's  rapid  growth,  no  one  can  tell  but  that  such  a  proposal 
may  be  adopted  within  the  next  decade.  It  would  be  a  work  of 
magnitude,  but  few  difficulties  would  be  encountered. 


CPIAPTER  XXVII 
DRY-LAND   DREDGING 

WITHIN  the  last  decade  dry-land  dredging  has  been  done  exten- 
sively in  America.  This  is  not  in  reference  to  excavation  work  by 
steam  shovels,  but  to  excavation  done  in  a  manner  somewhat 
similar  to  ordinary  dredging.  This  work  is  done  for  various  purposes, 
as  the  building  of  dykes  or  levees,  the  excavation  of  canals,  power 
ditches,  dams  and  reservoirs,  irrigation  and  drainage  ditches. 

The  machines  used  for  such  work  may  be  divided  into  two  classes. 
First,  types  of  machines  similar  to  those  used  in  ordinary  dredges. 
These  are  mostly  the  dipper,  grapple  and  hydraulic  suction  type, 
although  a  few  dredges  of  the  ladder  type  have  been  used.  One 
such  has  lately  been  used  in  the  state  of  Idaho,  in  excavating  irriga- 
tion canals.  The  dredge  is  of  a  fair  size,  and  is  operated  by  a  gasoline 
engine.  At  first  its  work  was  indifferent,  but  after  being  rebuilt 
it  has  done  efficient  work. 

Hydraulic  dredges  are  not  used  extensively,  but  more  so  than 
the  ladder  type  for  dry-land  work.  To  use  it  a  hole  large  enough 
to  float  the  machine  must  be  excavated  by  other  means  and  be 
filled  with  water.  A  supply  of  water  must  be  furnished  to  allow 
the  dredge  to  work.  Unless  the  work  is  situated  close  by  a  river  or 
large  body  of  water  the  needed  water  is  difficult  and  expensive 
to  obtain,  hence  it  is  only  possible  to  work  the  hydraulic  dredge 
under  special  conditions.  Land  however  is  sometimes  flooded  and 
excavated  with  such  dredges.  This  was  one  of  the  methods  suggested 
to  excavate  the  Culebra  cut  on  the  Panama  Canal  but  it  was  not 
adopted.  Other  objections  to  the  use  of  hydraulic  dredges  for 
dry-land  work  are  the  necessity  of  finding  a  place  to  deposit  the 
dredged  material  and  the  great  volume  of  water  necessary  to  carry 
it.  On  harbor  and  river  work  this  material  is  either  pumped  into 
another  part  of  the  harbor  or  river,  or  else  used  to  fill  up  adjoining 
lowlands  so  the  water  does  not  do  any  damage,  but  for  dry-land 
work,  even  if  there  is  a  place  to  deposit  the  dredged  material,  yet 

245 


246  A  TREATISE  ON  DREDGES  AND  DREDGING 

the  water  is  liable  to  do  damage  to  nearby  property.  At  times 
centrifugal  pumps  are  used  to  excavate  foundation  pits  and  coffer- 
dams. Such  pumps  are  mounted  on  platforms  or  skids,  and  are, 
as  a  rule,  of  a  smaller  size  than  those  used  on  dredges. 

Grapple  dredges  are  used  quite  extensively  for  dry-land  work. 
Both  clamshell  and  orange  peel  buckets  are  used  on  these  machines. 
In  some  cases  the  hoisting  machinery  is  simply  mounted  on  a  moving 
platform  or  skids  or  gunwales  and  the  bucket  is  operated  on  a 
derrick.  The  whole  machine  is  moved  either  on  rollers  or  wheels, 
and  is  operated  by  a  crew  of  three  or  four  men.  Even  sewer  trenches 
are  excavated  with  such  an  apparatus,  and  besides  the  various  kinds 
of  work  previously  mentioned,  railroad  embankments  and  levees 
are  sometimes  built  with  such  a  land  dredge.  On  extensive  work 
such  machines  are  often  worked  in  pairs.  Such  dredges  can  work 
in  hard  as  well  as  soft  materials,  and  will  work  both  in  dry  and  wet 
excavation.  These  buckets  are  also  used  in  foundation  work,  to 
excavate  inside  of  coffer-dams. 

Grapple  dredges  mounted  on  scows  are  also  used  on  dry-land 
work,  but  not  as  extensively  as  dipper  dredges.  When  there  is  no 
water  to  float  them  at  first,  a  pit  is  dug  and  water  pumped  or  turned 
into  it.  Both  are  used  in  a  manner  similar  for  such  dredges  in  rivers, 
except  in  canals  and  ditches  that  are  but  little  wider  than  the  scow, 
the  spuds  are  ou trigged  in  a  manner  somewhat  like  the  jack  arms 
of  a  steam  shovel,  and  are  held  in  place  on  the  banks  of  the  ditch. 
Such  spuds  are  called  "bank  spuds." 

Dipper  dredges  used  for  such  work  vary  in  size  from  dippers 
of  1  cu.yd.  or  less  up  to  10  or  12  cu.yds.  As  a  rule  the  excavated 
material  is  deposited  on  the  two  banks. 

Another  type  of  bucket  used  for  dry-land  work  is  shown  in 
Fig.  81.  These  are  used  on  long  derrick  booms,  and  in  some  cases 
by  means  of  a  deadman  set  ahead  of  the  machine  material  beyond 
the  reach  of  the  boom  is  excavated.  Such  buckets  are  in  nearly  all 
cases  patented.  The  best  known  are  the  Page,  the  Channon,  the 
Heyward,  the  Browning,  the  Austin  and  the  McCormick.  Some- 
times the  derricks  are  mounted  on  scows  and  then  used  as  a  dredge 
for  ditch  or  canal  excavation.  Locomotive  cranes  are  also  used 
to  operate  these  buckets,  as  well  as  orange  peel  and  clamshell 
buckets.  Some  manufacturers  also  rig  them  to  take  a  dipper  arm 
and  steam-shovel  dipper,  but  when  so  equipped  they  are  classed 
with  steam  shovels. 


DRY-LAND    DREDGING 


247 


The  second  class  of  dredges  used  for  dry-land  excavation  are 
machines  designed  and  built  for  this  particular  kind  of  work. 
One  of  the  best  known  of  these  machines  is  the  Austin  Drainage 
Excavator,  built  by  a  company  of  that  name,  in  Chicago,  111.  This 
machine  straddles  the  ditch  or  canal  and  excavates  a  clean  ditch 
with  sides  sloped  to  any  desired  angle,  see  Fig.  82.  Digging  with 
this  machine  is  often  termed  " excavating  a  ditch  to  a  template." 


FIG.  81. — Bucket  for  Dry-land  Dredging. 

A  steel  framework  upon  which  the  two  buckets  operate  is  made 
to  conform  to  the  bottom  of  the  ditch  and  extend  to  either  side, 
so  that  the  earth  is  carried  away  from  the  sides  of  the  ditch,  leaving 
a  berm  that  is  free  of  earth,  and  thus  preventing  it  from  running 
back  into  the  excavation.  In  this  manner  two  regular  levees  are 
built,  one  on  each  side  of  the  ditch,  that  act  as  banks  to  confine 
the  water  in  case  of  floods.  The  berm  left  is  from  10  to  15  ft.  wide. 
The  frame  under  the  machine  is  lowered  as  the  ditch  is  deepened. 


248 


A  TREATISE  ON  DREDGES   AND   DREDGING 


The  buckets  travel  forward  and  backward  on  the  frame,  cutting 
off  a  thin  slice  of  earth  from  the  sides  and  bottom.  As  one  bucket 
is  being  dumped  the  other  is  loading.  The  excavation  can  be  made 
either  in  the  dry  or  under  water.  No  dirt  is  left  in  the  bottom, 
the  buckets  cleaning  it  up  as  the  machine  travels  along  on  two  rails, 
one  on  either  side  of  the  ditch.  As  the  dredge  travels  on  rails  a 
perfectly  straight  ditch  can  be  dug.  It  can  also  be  mounted  on  a 
walking  device  or  on  a  scow,  but  its  best  work  is  done  when  operated 
on  rails.  The  guiding  frame  can  be  raised  above  the  surface  of  the 


FIG.  82. — The  Austin  Drainage  Excavator. 


ground,  and    thus  be  moved   across  the  country  on  its  own  rails, 
traveling  under  favorable  conditions  about  a  mile  per  day. 

J.  W.  T.  Stephens  of  New  Orleans,  La.,  is  the  inventor  of  a  small 
dredge  for  ditch  and  canal  work.  It  might  be  classed  with  the 
ladder  or  elevator  type  of  machines.  The  chain  of  buckets  is  hung 
from  a  boom  and  discharge  onto  belt  conveyors,  depositing  the 
material  onto  either  bank.  Bank  spuds  or  arms  hold  the  dredge 
or  scow  in  place.  The  boom  can  be  raised  or  lowered  and  swung 
from  side  to  side,  covering  180  °  of  circle,  so  that  from  one 
position  of  the  boat,  a  large  amount  of  work  can  be  done.  The 


DRY-LAND  DREDGING  249 

. 

banks  of  the  ditch  can  be  sloped  as  the  ditch  is  excavated  with 
this  machine. 

The  Fairbanks  Steam  Shovel  Co.,  of  Marion,  O.,  manufactures  a 
ditching  machine  known  as  a  "walking  dredge."  Such  a  machine 
is  meant  for  ditch  work  where  there  is  not  enough  water  to  float  a 
boat.  The  machinery  is  placed  on  a  timber  hull  that  reaches  over 
the  constructed  ditch.  The  boom  is  operated  by  a  turntable,  and 
attached  to  the  boom  is  the  scraper-like  shovel,  with  a  capacity  of 
from  1  to  2  cu.yds.  The  long  scraper  arm  reaches  down  into  the 
ditch,  and  the  bucket  or  scraper  is  filled  by  means  of  a  drag  line 
from  the  engine.  The  scraper  has  two  bails  and  two  lines  on  it. 
The  second  bail  keeps  the  bucket  in  an  upright  position  while  being 
loaded,  and  by  releasing  the  line  the  bucket  is  dumped.  The 
machine  is  named  from  the  method  of  moving  it  over  the 
ground. 

Another  type  of  walking  dredge  has  been  used  in  Minnesota  on 
drainage  work.  This  machine  has  a  second  boom,  known  as  the 
walking  beam,  suspended  from  the  boom.  The  scraper  or  bucket 
is  attached  to  this  second  boom,  and  instead  of  working  toward 
the  machine,  it  works  away  from  the  dredge  when  loading.  This 
is  done  by  means  of  a  chain  attached  to  the  walking  arm,  and  the 
'load  is  released  by  a  chain  on  the  other  side  of  the  arm.  The  follow- 
ing description  is  taken  from  the  bulletin  of  the  Northeastern  Experi- 
ment Farm  of  the  University  of  Minnesota. 

"The  peculiarity  of  this  machine  is  the  method  of  moving. 
Under  each  corner  is  a  timber  platform  the  shape  of  a  stoneboat, 
called  a  foot.  Each  of  these  corner  feet  is  6  ft.  wide,  8  ft.  long  and 
4  in.  thick.  They  are  joined  together  transversely  by  a  light  timber. 
This  requires  them  both  to  move  in  the  same  direction,  the  direction 
being  controlled  by  a  chain  which  runs  from  each  corner  foot  *o 
a  drum  that  is  operated  by  the  cranesman.  Near  the  outside  of 
each  corner  foot  there  is  a  knife  made  of  iron,  J  in.  thick  by  6  in. 
wide  and  6  ft.  long,  which  prevents  the  foot  slipping  sidewise. 
Midway  of  the  machine  on  either  side  is  a  center  foot  6  ft.  wide, 
14  ft.  long  and  6  in.  thick.  On  the  under  side  a  6X6  in.  timber 
is  bolted  crosswise,  to  prevent  slipping  back.  This  foot  is  attached 
to  a  heavy  triangle  frame,  free  to  move  longitudinally  between 
the  double  side  frame  of  the  hull.  A  chain,  the  end  of  which  is 
attached  to  the  side  timbers  of  the  hull,  passes  over  two  pulleys 
in  this  triangular  frame  and  then  passes  along  the  hull  to  the  back 


250  A  TREATISE   ON   DREDGES  AND  DREDGING 

corner  and  across  the  back  end  to  a  drum  which  is  located  about 
the  center  of  the  hull.  When  it  is  desired  to  move  the  machine 
the  power  is  turned  on  to  this  drum  and  the  chain  wound  up.  As 
the  chain  tightens,  the  hull  of  the  machine  rises,  the  weight  coming 
on  the  center  foot.  The  winding  on  the  drum  is  continued  until 
the  weight  in  lifting  the  hull  becomes  greater  than  the  friction  at 
the  corner  feet,  when  the  entire  hull  moves  ahead  about  6  ft.,  although 
an  8-ft.  move  can  be  made.  The  chain  is  then  released,  taking 
the  weight  off  the  center  foot,  which  is  pulled  by  another  chain 
attached  to  a  drum  in  the  front  part  of  the  hull. " 

This  machine  has  moved  across  country  at  the  rate  of  1  mile 
in  11  hrs.  The  dredge  has  excavated  7  scrapers  of  earth  and  moved 
ahead  6  ft.  8  in.  in  7  minutes.  This  is  said  to  be  an  average  speed. 
Difficulty  is  experienced  in  excavating  in  soft  material,  and  also 
in  making  short  turns  with  the  machine,  owing  to  cave-ins. 

In  the  same  bulletin  is  described  the  Junkin  ditcher,  which 
consists  of  a  car  running  on  rails,  one  on  each  side  of  the  ditch. 
As  in  the  Austin  machine  a  steel  frame  extends  under  and  over 
the  machine,  and  is  operated  in  a  somewhat  similar  manner. 

"At  the  back  of  the  car,  transversely  to  the  direction  of  the 
ditch,  is  a  triangular-shaped  cutting  frame,  the  lower  part  of  which 
is  constructed  to  conform  to  the  bottom  and  slopes  of  the  proposed 
ditch.  Over  each  half  of  this  frame  are  two  chain  belts  30  in.  apart, 
and  between  these  belts  are  riveted  at  equal  distances  14  buckets, 
which  excavate  and  carry  the  material.  The  cutting  edge  of  these 
buckets  can  be  detached  from  the  main  part  for  sharpening  if  occasion 
requires.  The  buckets  over  each  half  of  the  frame  travel  in  opposite 
direction,  so  that  each  set  passes  up  the  slope  of  the  ditch,  where 
it  does  the  excavating.  Their  direction  is  changed  at  the  apex  of  the 
triangle  by  sheaves,  each  bucket  making  a  complete  revolution 
every  45  seconds,  although  in  easy  digging  they  can  run  at  a  speed 
of  two  revolutions  per  minute.  The  excavating  frame  can  be  put 
together  in  such  a  manner  that  it  will  cut  a  narrow  or  wide  bottom, 
or  different  slopes.  The  excavated  material  is  cut  up  very  fine 
and  deposited  on  either  bank.  The  spoil  banks  have  uniform  slopes 
coming  to  a  sharp  edge  at  the  top." 

The  dredge  excavates  a  strip  30  in.  wide  at  one  time,  and  as  it 
leaves  a  ridge  in  the  center  of  the  ditch  or  canal,  after  making 
an  advance  of  30  ft.  it  goes  back  to  clean  up  the  slopes  and  the 
loose  material  it  leaves.  The  ridge  can  be  shoveled  out  by  hand 


DRY-LAND   DREDGING  251 

• 

or  left  to  be  washed  away  by  the  action  of  the  water,  extra  material 
being  taken  out  so  as  to  bring  the  bottom  back  to  grade. 

The  straddle  ditching  machine  is  built  by  Mayer  Brothers,  Inc., 
of  Mankato,  Minn.  It  is  mounted  on  two  steel  beams  that  straddle 
the  ditch  to  be  excavated.  The  four  ends  of  these  beams  are  provided 
with  a  two-wheel  oscillating  truck,  which  runs  on  plank  ways,  6  in. 
thick  and  3  ft.  wide,  built  in  20  ft.  sections.  These  plank  ways 
are  moved  forward  by  two  special  cranes  provided  on  the  dredge 
for  that  purpose.  The  whole  machine  is  moved  ahead  by  means 
of  a  cable  run  to  a  deadman  in  front,  without  interfering  with  the 
work  of  the  dredge.  In  other  respects  the  straddle  ditching  machine 
is  like  a  dipper  dredge. 

A  number  of  steam-shovel  manufacturers  make  some  types  or 
type  of  ditching  machine  to  be  mounted  on  a  scow  for  working 
either  for  dry-land  excavation  or  when  there  is  water.  These  all 
have  dippers  and  we  need  not  comment  on  them  further. 

It  is  but  natural  that  most  dry-land  excavation  is  done  by  other 
means  than  dredges,  but  dredges  are  being  used  more  and  more 
for  such  work,  as  it  is  found  to  be  economical,  especially  when 
large  quantities  are  to  be  moved.  Another  method  of  dry-land 
excavation  is  by  means  of  a  jet  of  water.  This  is  known  as  hydraulic 
sluicing  and  is  done  by  means  of  a  nozzle,  known  as  a  monitor  or 
giant.  This  method  is  used  also  for  mining,  and  earth  is  loosened 
and  in  some  cases  elevated  by  means  of  hydraulic  elevators,  which 
are  described  elsewhere. 

The  Chicago  Drainage  Ganal,  built  during  the  nineties,  was  a 
case  of  dry-land  excavation,  upon  which  many  different  classes  of 
machines  were  used,  including  dredges,  steam  shovels  and  cable- 
ways.  A  large  number  of  special  machines  were  also  designed  for 
this  work,  and  when  grapple  buckets  were  used  on  them,  they 
could  be  classed  with  dredges,  but  the  majority  of  such  machines 
were  designed  to  dispose  of  the  spoil  and  not  to  excavate  it. 

The  rebuilding  of  the  Erie  Canal  in  New  York  State  into  a  1000- 
ton  barge  canal,  is  also  another  example  of  dry-land  excavation 
that  has  brought  out  special  machines,  and  a  number  of  large  dredges 
for  carrying  on  the  excavation.  Power  scrapers  are  being  used 
both  with  movable  derricks,  derrick  cars  and  cableways,  and  grapple 
buckets  have  been  operated  by  means  of  a  large  steel  overhead 
bridge  near  Rochester,  N.  Y. 

The  Panama  Canal  is  the  greatest  undertaking  that  the  world 


252  A  TREATISE  ON  DREDGES  AND   DREDGING 

has  ever  seen  in  connection  with  earth  and  rock  excavation.  Steam 
shovels  and  dredges  are  being  used  for  this  work  almost  exclusively. 
The  dredges  are  of  the  suction,  ladder,  and  dipper  type.  Some 
are  of  the  hopper  type.  In  spite  of  the  fact  that  this  is  the  greatest 
job  of  excavation  undertaken  by  man,  there  have  been  no  new  types 
of  machines  invented  or  designed  for  the  work,  owing  to  the  fact 
that  the  U.  S.  Government  is  doing  the  work  by  day  labor, 
instead  of  employing  contractors,  who  would  no  doubt  have  reduced 
the  cost  of  the  excavation  by  using  machines  designed  especially 
for  the  job  in  hand. 


CHAPTER  XXVIII 
THE  COST   OF   OPERATING   DREDGES 

THE  cost  of  dredging,  like  that  of  any  other  engineering  work, 
should  be  deduced  from  an  accurate  analysis  of  all  the  various 
operations  required  for  the  work.  Some  of  these  expenses  are  very 
apparent,  recurring  continuously  in  the  execution  of  the  work, 
while  others,  and  perhaps  the  most  important,  do  not  occur  simul- 
taneously with  the  work,  but  at  long  intervals  between  one 
another,  thus  they  are  detected  with  more  difficulty  and  in  many 
cases  observed. 

Some  engineers  and  contractors,  in  preparing  estimates  for  public 
works,  rely  almost  exclusively  upon  the  prices  that  were  paid  for 
works  executed  under  almost  similar  circumstances,  this  method 
of  determining  the  cost  of  wrork  very  often  leading  to  errors.  Prices 
will  give  but  little  idea  of  costs,  unless  the  profit  realized  by  the 
contractor  can  be  learned.  Since  such  information  can  hardly  be 
obtained,  it  is  evident  that  prices  are  hardly  a  guide  for  bidding 
on  new  works.  Besides,  in  dredging  it  is  difficult  to  call  work 
similar,  owing  to  the  different  conditions  of  depth,  magnitude 
of  the  improvement,  quality  of  soil,  whether  the  dredging  is  to 
be  done  in  the  open  or  in  sheltered  places,  the  character  of  the 
plant  and  other  details.  Useful  information  concerning  the  cost 
of  dredging  may  be  obtained  from  the  annual  reports  of  the  Chief 
of  engineers  of  the  United  States  Army.  In  them  is  given  the  cost 
of  various  improvements  in  different  sections  of  the  country.  There 
are  at  present  many  government  dredges  engaged  on  difficult  works 
about  the  country.  These  dredges  are  handled  by  experienced 
engineers  and  crews  and  their  work  may  certainly  give  an  approximate 
idea  of  the  real  cost  of  dredging.  But  even  such  data  should  be 
taken  with  great  caution,  owing  to  the  fact  that  the  reports  frequently 
do  not  include  expenses  which  should  be  charged  to  the  work. 
Thus,  for  instance,  the  salary  of  engineers,  the  tugs  or  motor  boats 
for  the  service  of  engineers  and  crews,  the  cost  for  piers,  the  cost 

253 


254  A  TREATISE  OX  DREDGES   AND   DREDGING 

of  coaling  and  repairing  the  dredges,  office  expenses  and  other 
items.  These  are  not  charged  to  dredging  in  the  government 
reports,  while  they  are  very  expensive  items  to  a  contractor. 
Another  item  which  the  government  reports  do  not  show  is  the 
contractor's  profit,  which  must  cover  his  own  work  and  the  risks 
he  must  incur.  Also,  the  interest  of  the  money  invested  in  the 
plant  is  given  too  low  in  the  government  reports,  as  it  is  evident 
that  a  private  contractor  cannot  obtain  money  at  the  same  low 
interest  as  the  government.  Hence  even  the  accurate  data  furnished 
by  these  annual  reports  should  be  handled  with  great  care  by 
engineers  and  contractors. 

The  proper  way  to  correctly  determine  the  cost  of  dredging  is  to 
make  an  accurate  analysis  of  all  the  items  of  expense  required  for 
the  work  under  consideration.  The  expenses  of  dredging  may  be 
classified  in  two  groups,  namely:  those  concerning  the  plant  and 
the  general  expenses  required  for  the  execution  of  the  work.  In 
regard  to  the  plant  the  expenses  can  be  again  divided  into  operating 
expenses  or  those  required  every  day  for  the  running  of  the  dredge, 
and  into  yearly  expenses,  being  interest  and  depreciation  on  the 
plant  and  interest  on  the  capital  invested.  These  must  be  prorated 
over  the  length  of  the  season  worked. 

Operating  Expenses.  The  field  or  operating  expenses  include 
all  the  expenses  required  for  running  the  plant  in  such  a  manner 
as  to  obtain  the  greatest  efficiency  with  the  minimum  effort. 
The  operating  expenses  include  those  absolutely  necessary  for  the 
removal  of  materials  from  the  bottom,  as  well  as  those  required  for 
the  transportation  of  the  dredged  materials  to  their  final  destination. 
Thus  the  operating  expenses  vary  with  the  machine  employed 
and  the  method  of  transportation  of  the  debris.  In  the  hydraulic 
dredges  as  well  as  in  the  dredges  of  the  sea-going  hopper  type  the 
principal  expenses  are  those  required  for  the  handling  of  the  machin- 
ery to  keep  it  in  perfect  working  order;  but  when  the  materials 
must  be  transported  on  scows,  towed  by  tugboats,  besides  the  running 
expenses  as  indicated  above,  there  is  also  the  cost  of  hauling  the 
scows.  Thus  in  regard  to  the  operating  expenses  a  distinction 
should  be  made  concerning  the  character  of  the  machine  employed — 
as  dredges  of  the  hopper  type;  dredges  in  which  the  transportation 
of  the  material  is  effected  by  scows  towed  by  tugboats,  and  dredges 
in  which  the  debris  is  conveyed  to  land  by  means  of  pipes  or  other 
devices. 


THE  COST   OF  OPERATING  DREDGES  255 

f 

In  the  sea-going  hopper  dredge  the  most  important  operating 
expenses  are  the  wages  of  the  officers  and  crew  handling  the  machine. 
As  a  rule  there  are  always  two  crews  on  board  of  these  steamer 
dredges,  in  order  to  work  continuously  day  and  night.  Other 
important  items  of  expenses  are  the  consumption  of  coal ;  the  repairs 
which  are  absolutely  necessary  to  keep  the  machines  in  good  working 
order;  the  subsistence  of  the  crew  and  officers  compelled  to  live  on 
board  the  steamer;  besides  miscellaneous  supplies,  as  water,  etc. 
In  the  sea-going  hopper  dredge  either  of  the  hydraulic  or  ladder 
types,  the  various  items  of  the  operating  expenses  are  more  or  less 
in  the  following  proportions: 


' 33% 

Coal 25 

Repairs 25 

Subsistence .'  10 

Miscellaneous 7 

Total. 100% 

When  the  dredged  materials  are  transported  to  the  dumping 
place  by  means  of  scows  towed  by  tugboats,  the  cost  of  transpor- 
tation represents  the  highest  item  of  the  operating  expenses.  Dredges 
served  by  scows  as  a  rule  work  only  in  daytime,  consequently  one 
crew  is  sufficient  to  handle  the  machine  during  its  work;  thus  the 
expenses  concerning  the  wages  of  the  crew  and  their  subsistence 
are  comparatively  small.  In  general  it  may  be  said  that  in  dredges 
served  by  scows  the  various  operating  expenses  are  in  the  following 
proportions : 

Transportation  of  scows 40% 

Wages 22 

Repairs 18 

Coal : '..., 12 

Board 6 

Miscellaneous 2 

Total 100% 

In  dredging,  the  coal  consumption  is  comparatively  a  small  item 
when  compared  with  other  expenses.  Consequently  high-tower 
ladder  dredges  are  not  as  economical  as  they  seem,  and  could  be  more 
extensively  used  to  advantage  in  some  particular  cases.  For  making 
a  rough  estimate  the  coal  consumption  can  be  figured  about  1  cent 
per  cubic  yard  of  dredged  material,  provided  the  price  of  coal  is 
$3.00  per  ton. 


256 


A  TREATISE   OX   DREDGES   AND   DREDGING 


Repairs  represent  another  important  item  of  expense.  They 
should  include  only  the  repairs  that  occur  almost  even'  day  and 
are  necessary  for  the  continuous  working  of  the  machine.  They 
do  not  include  the  general  overhauling  of  the  dredge,  generally 
done  once  a  year  or  at  the  close  of  the  season.  Mr.  Babcock,  dis- 
cussing this  item  of  expense  in  connection  with  the  hydraulic 
hopper  dredges  "Manhattan"  and  "Atlantic"  states  that  the  value  of 
the  time  lost  due  to  repairs  far  exceeds  the  actual  cost  of  the  repairs. 
He  calculates  that  the  value  of  time  lost  by  reason  of  repairs  in 
eleven  months  was  $110,538,  while  the  money  actually  paid  for 
these  repairs  was  only  $43,721. 

The  total  amount  of  the  operating  expenses  in  a  month,  season 
or  year  divided  by  the  total  quantity  of  material  removed  in  the 
same  length  of  time,  will  give  the  cost  of  the  unit  of  volume  of  the 
excavated  material.  It  is  evident  that  all  items  of  expense  remain- 
ing the  same,  the  greater  the  amount  of  material  excavated  the 
smaller  will  be  the  cost  per  unit  of  volume.  Numerous  delays 
from  various  causes  tend  to  increase  the  cost.  Thus  it  may  be 
said  that  the  operating  expenses,  per  unit  of  volume,  are  inversely 
proportional  to  the  quantity  of  material  removed,  and  directly 
to  the  delays.  The  following  table,  taken  from  Engineering,  June 
19,  1903,  shows  the  percentage  of  time  worked  and  the  delays  for 
an  average  of  one  year's  work,  of  several  dredges  of  different  types 
employed  on  improvement  work  in  New  South  Wales: 


Twelve  Ladder 
Dredges. 

Ten  Hydraulic 
Dredges. 

Seven  Hydrau- 
lic and 
Grab  Dredges. 

Twelve  Grab 
Dredges. 

Dredging  

63% 

49% 

61% 

62% 

Coaling 

o 

2 

2 

3 

Removals        

9 

14 

16 

8 

Bad  weather 

3 

2 

0 

3 

Waiting  points  

3 

2 

Repairs 

19 

25 

16 

15 

Other  causes     

1 

1 

3 

7 

Taking  silt  to  sea 

7 

100% 

100% 

100% 

100% 

For  the  time  occupied  in  the  various  operations  by  the  hydraulic 
hopper  dredges  "Manhattan"  and  "Atlantic, "working eleven  months 
each,  from  July  1,  1905,  to  May  31,  1906,  as  given  by  Mr.  Babcock, 
in  Engineering  News,  see  Vol.  LVI,  p.  306: 


THE   COST  OF   OPERATING   DREDGES 


257 


Whole 

Parts  o 

f  Days. 

Total 
in  Days 

Percent- 

Days. 

Hours. 

Minutes. 

of  24 
Hours. 

age. 

Actually  at  work                      

8041 

38 

335  1 

50  0 

Repairing    

112 

628 

05 

138  1 

20  6 

Fog  and  snow 

272 

40 

11  5 

1  7 

Storm                     .      

6 

177 

15 

13  4 

2  0 

Taking  on  coal,  etc.,  minor  repairs  and 
clearing  up;  parts  of  Saturdays  and 
Mondays        

1102 

37 

46  0 

6  9 

Miscellaneous                              .  .  . 

89 

35 

3  7 

0  6 

In    July,    1905,    before    night    work 
began  

294 

12  2 

1  8 

Sundays  and  holidays  

110 

110.0 

16.4 

670.0 

100.0 

In  the  dredge  "Fin.  MacCool"  employed  at  the  Buffalo  Break- 
water during  the  season  May-October,  1899,  working  from  12  to 
14  hours  per  day,  the  proportion  of  the  time  employed  in  dredging 
and  that  lost  in  delays,  was,  according  to  Mr.  Emile  Low  (Engineer- 
ing News,  October,  1906),  as  follows: 


Time  Worked. 
Hrs.       Min. 

Time  Delayed. 
Hrs.        Min. 

Number  of 
Days. 

Length  of  Days 
in  Hours. 

May 

190      37 
232       11 
211       40 
255       31 
133       12 
98       02 

131 
131 
152 
122 
206 
55 

23 

49 
20 
29 

48 
46 

23 
26 
26 
27 
24 
13 

14 
14 
14 
14 
14 
12 

June                   .    .    . 

July 

August 

September  

October 

Total  

1121       13 

800 

35 

139 

which  shows  that  the  time  employed  in  dredging  was  58  per  cent, 
while  42  per  cent  of  the  total  time  was  lost  in  delays.  Mr.  Low 
indicates  also  the  various  causes  of  delay  together  with  the  time 
lost  for  these  causes: 


Item  of  Delay. 

Hoist  cables 

Total. 
Hrs.  Min. 

24     55 

Item  of  Delay. 
Waiting  for  scows  

Total, 
Hrs.  Min. 

29     54 

Clam.             

101     40 

Waiting  for  tugs  

9     37 

Main  engines 

4     55 

Meals       

...    125     40 

Boilers                    .            

1     05 

Rain  and  fog  

4     15 

Anchors  and  attachments 

7     20 

Sea  

317     35 

A  frame  and  boom  
Breakdowns    dredge           .  .  . 

6     15 
0     35 

Moving  and  placing.  .  . 
Miscellaneous  

67     49 
36     26 

Leaking  scows 

1     05 

Holidays,  etc  .  .  :  

42     53 

Repairing  sc"ows  

14     51 

Siohoninff  scows.  . 

3     47 

Total  .  . 

.   800     35 

258  A  TREATISE  ON  DREDGES   AXD   DREDGING 

Annual  Expenses.  In  the  annual  expenses  are  included  the 
interest  of  the  capital  invested  in  the  plant,  the  sinking  fund,  insur- 
ance, taxes,  profit  of  contractor,  general  expenses,  etc. 

The  dredging  plant  required  for  any  harbor  or  river  improvement 
as  a  rule  is  very  expensive,  being  composed  of  complicated  and 
large  machinery  and  numerous  boats  which  necessitate  the  invest- 
ment of  a  large  capital.  This  capital  if  invested  in  any  other  way 
would  certainly  yield  a  profit,  according  to  the  conditions  of  the 
market,  of  4  or  5  per  cent  per  year.  Consequently  it  cannot  be 
said  that  the  work  performed  by  the  machines  has  given  a  certain 
profit  unless  this  interest  has  been  deducted.  In  dredging,  owing 
to  the  large  capital  invested  in  the  plant,  this  interest  charge  is 
not  likely  to  be  overlooked,  as  when  the  plant  is  owned  by  private 
contractors,  it  is  sometimes  heavily  mortgaged,  and  when  owned 
by  a  public  corporation,  it  has  been  acquired  with  money  obtained 
from  an  issue  of  bonds,  on  which  yearly  interest  must  be  paid. 
In  any  case  the  engineers  should  deduct  from  the  gross  profit  the 
amount  corresponding  to  at  least  5  per  cent  of  the  total  value  of 
the  plant  on  hand. 

The  life  of  any  contractor's  plant,  especially  one  used  for  dredging, 
is  comparatively  short.  Notwithstanding  the  continuous  repairs 
which  are  made  to  the  machine  while  at  work,  and  the  general 
overhauling  which  is  usually  given  at  the  end  of  each  working  season, 
the  machine  depreciates  continuously.  The  repairs  increase  from 
year  to  year,  until  a  point  is  reached,  when  to  keep  the  machine 
in  working  order,  the  expenditure  required  will  be  such  as  to  justify 
the  purchase  of  a  new  machine.  From  the  yearly  gross  profits  of 
the  business  a  sinking  fund  should  be  set  aside,  so  as  to  accumulate 
money  to  purchase  a  new  dredge.  In  a  word  the  same  method 
must  be  used  as  for  determining  a  sinking  fund.  It  is  difficult  to 
determine  the  life  of  a  dredge,  ^ince  it  could  be  extended  by  constant 
repairing  for  many  years,  but  as  a  rule  the  life  of  the  dredge  is 
estimated  to  be  from  15  to  20  years.  At  the  end  of  this  period, 
the  machine,  although  greatly  depreciated,  will  as  junk  still  have 
a  certain  value,  probably  about  10  per  cent  of  the  original  cost. 
The  annuity  or  amount  of  money  to  be  set  aside  from  the  gross 
profit  of  the  undertaking  should  be  such  that  at  the  end  of  15  or 
20  years  will  give  an  amount  equal  to  nine-tenths  of  the  original 
cost  of  the  plant. 

Another    item    of   annual   expense  is  the   general  overhauling 


THE  COST   OF  OPERATING  DREDGES  259 

of  the  plant  at  the  end  of  each  working  season.  All  the  various 
machines  should  be  looked  over  carefully  and  the  parts  that  have 
been  worn  should  be  replaced.  Gears,  chains,  ropes  showing  indi- 
cation of  weakness  should  be  replaced  with  new  ones.  All  the  timber 
should  be  kept  in  first  class  order,  well  caulked  and  painted,  and  if 
the  hulls  of  the  dredge  and  boats  are  made  of  steel  they  should  be 
cleaned,  scraped  and  painted  before  being  put  in  commission  again. 
It  is  difficult  to  estimate  accurately  this  item  of  expense,  but  when 
all  the  most  important  repairs  have  been  made  during  the  season 
and  the  plant  has  been  kept  in  good  working  order,  10  per  cent  of  the 
total  cost  of  the  plant  should  be  sufficient  to  cover  all  the  expenses 
required  for  the  general  overhauling. 

The  dredging  plant  should  be  insured  against  fire  and  maritime 
accidents.  The  annual  premiums  for  carrying  these  two  insurances 
are  not  heavy.  Without  more  definite  data,  an  amount  equal  to 
2  or  3  per  cent  of  the  total  value  of  the  plant  should  be  set  aside 
for  covering  both  the  premiums  of  the  fire  and  maritime  insurance. 

General  expenses,  as  office  rent,  the  renting  of  piers  for  mooring 
the  dredges  and  tugboats  during  repairs  and  while  not  at  work, 
the  salaries  of  the  engineers,  superintendents,  office  clerks,  all  the 
taxes,  office  and  traveling  expenses  should  be  deducted  from  the 
gross  profits  of  the  enterprise.  In  estimating  without  other  data 
at  hand,  an  amount  varying  between  5  and  15  per  cent  of  the  total 
amount  of  work  done  should  cover  general  expenses.  Five  per 
cent  of  the  total  cost  should  be  sufficient  in  case  of  large  and  extensive 
jobs,  while  for  smaller  ones,  the  general  expenses  should  be  estimated 
at  15  per  cent  of  the  total  cost. 

Another  important  item  is  the  contractor's  profit.  He  is  entitled 
to  a  profit,  not  only  for  the  time  and  knowledge  given  to  the  work, 
but  also  for  the  many  risks  that  he  runs.  Ample  compensation 
should  be  allowed  him.  It  is  difficult  to  state  the  percentage  to 
allow  for  this  item,  but  it  is  generally  safe  not  to  put  it  down  for 
less  than  10  or  15  per  cent.  This  should  be  sufficient  for  large 
undertakings,  but  for  smaller  jobs  a  larger  percentage  must  be 
allowed,  and  also  for  working  in  dangerous  and  exposed  places. 


CHAPTER  XXIX 
COST  DATA 

IN  this  chapter  are  given  some  examples  illustrating  the  cost 
of  dredging  with  different  types  of  machines.  They  are  taken  from 
articles  published  in  technical  papers,  and  have  been  slightly 
condensed.  The  following  examples  are  given  in  order: 

1.  The  work  of  the  ladder  dredge  "  Percy  Sanderson  "  used  at 

Salina,  mouth  of  the  Danube  River. 

2.  The  cost  of  dredging  with  the  hydraulic   sea -going  hopper 

dredges  "  Manhattan  "  and  "Atlantic  "  as  used  in  the  Ambrose 
Channel,  New  York,  and  with  the  stationary  hydraulic  dredge 
used  at  Wilmington,  Cal. 

3.  The  cost  of  dredging  with  small  dipper  dredges  used  by  U.S.A. 

engineers  in  the  harbors  and  rivers  of  different  parts  of 
the  country. 

4.  The  cost  of  dredging  with  the  clamshell  dredge  "  Fin  MacCool," 

used  at  Buffalo  Breakwater,  and  described  by  Mr.  Emile 
Low  in  Engineering  News. 


The  cost  of  dredging  with  the  sea-going  hopper  ladder  dredge 
"Percy  Sanderson,"  used  at  Salina,  mouth  of  the  Danube  River, 
is  taken  from  a  paper  by  Mr.  C.  H.  Kuhl,  M.  I.  C.  E.,  published 
in  Engineering  (London)  December,  1901. 

Regarding  the  cost  the  quality  of  the  material  to  be  dredged 
is  the  most  important  factor.  A  shallow  cut  on  an  uneven  bottom 
naturally  gives  very  unfavorable  results.  At  Salina,  the  worst 
year  was  1896,  when  the  cost  of  dredging,  transporting  and  discharg- 
ing sand  and  silt  was  5d.  per  cu.yd.  The  best  year  was  1899,  when 
the  cost  with  clay  only  came  to  2. Id.  per  cu.yd.  The  average 
price  is  4.2d.  per  cu.yd.  for  dredging  1,790,736  cu.yds.  from  1894 
to  1899,  including  all  expenditure  for  repairs,  renewals  and  liberal 

260 


COST   DATA 


261 


maintenance  of  the  dredger,   but  excluding  interest,  depreciation 
and  insurance. 

Dredge   "Percy   Sanderson"   was  built    at   a   cost   of  £32,423, 
and  dredged  the  following  quantities  from  Salina  entrance  channel. 


Dredging  channe, 


Maintenance  from  j  between  piers "...   224,028 

1895  to  1900       \  outside 796,395 


987,717  cu.yds. 
1,020,423 


Total. 


2,008,140 


These  quantities  were  excavated  in  the  years  and  localities  as 
indicated  in  the  following  table: 


Between 

the  Piers. 

At  S 

ea. 

Old  Ground. 

New  Ground. 

Old  Bank. 

New  Deposit. 

Total. 

1894 

Cubic  Yards. 
109,070 

Cubic  Yards. 

Cubic  Yards. 

Cubic  Yards. 

109,070 

1895 
1896 

1897 

92,585 

5,148 
101,241 
22  102 

202,021 
16,398 

65,069 
155,426 
265  222 

364,823 
273,065 
287  324 

1898 

14,259 

143,306 

188,259 

325,824 

1899 

67019 

363  611 

430  630 

1900 



14,259 

60,726 

142,419 

217,404 

NUMBER  OF  LOADS  DREDGED  AND    REMOVED    PER    MONTH    BY 
THE   DREDGE    "PERCY  SANDERSON" 


Month. 

1894. 

1895. 

1896. 

1897. 

1898. 

1899. 

1900. 

January   

37 

14 

February 

40 

3 

March        .  . 

55 

5 

41 

April  

32 

12 

39 

18 

May 

60 

36 

57 

74 

June  

64 

40 

49 

79 

110 

July 

85 

57 

55 

79 

113 

76 

August     

60 

54 

77 

108 

61 

September 

67 

86 

8 

45 

92 

86 

October  

42 

29 

42 

45 

88 

82 

November 

30 

30 

40 

93 

December  

59 

21 

131 

529 

383 

403 

457 

604 

305 

262 


A  TREATISE  ON  DREDGES  AND  DREDGING 


DREDGE  "PERCY  SANDERSON."  RECORD  OF  TIME  WORKED  AND 

QUANTITY  DREDGED 


Quan- 

Quan- 

Year. 

Full 
Days. 

Parts 
of 
Days. 

Total 
Days. 

Under 
Steam. 

Actual 
Dredg- 
ing. 

Total 
Quantity 
Dredged. 

tity 
Dredg- 
ed per 
Work- 

tity 
Dredg- 
ed per 
Work- 

Remarks. 

ing 

ing 

Day. 

Hour. 

H.     M. 

H.      M. 

Cu.Yds. 

Cu.Yds. 

Cu.Yds. 

1894 

36 

18 

54 

900   10 

192   30 

109,070 

2020 

567 

Clay 

1895 

153 

43 

196 

3546  20 

1058  17 

364,823 

1861 

345 

Clay  and  sand 

1896 

129 

34 

163 

3090  10 

967  10 

273,065 

1675 

282 

Sand  and  silt 

1897 

126 

41 

170 

2921  40 

1113  45 

289,324 

1690 

258 

Sand  and  silt 

1898 

114 

32 

146 

2401  20 

917  35 

325,824 

2232 

355 

Clay  and  sand 

1899 

114 

25 

139 

2271  50 

843  45 

430.630 

3098 

510 

Clay 

1900 

67 

25 

92 

1428     5 

543  50 

217^454 

1823 

308 

Sand  and  silt 

COST  OF  DREDGING,  INCLUDING  REPAIRS  AND  MAINTENANCE  OF 

DREDGE 
(Quantity  dredged  1894-99,  1,790,736  cu.yds.) 

d.  d. 

Dredging:         Coal  and  stores 0 . 81  \    9  Q~ 

Crew  and  wages 1 . 24  / 

Repairs,  etc.:  Coal  and  stores 1 . 02  1    „  17 

Crew  and  wages 1 . 15  J 

Total  per  cubic  yard  dredging  and  repairs 4 . 22 

Interest,  depreciation,  and  insurance  not  included. 

The  marine  dredge  "Percy  Sanderson,"  built  by  Messrs.  William 
Simons  &  Co.  of  Renfrew,  is  220  ft.  long,  40  ft.  broad  and  17  ft.  2 
in.  deep.  The  hopper  carries  1250  tons.  The  30  buckets  have  each  a 
capacity  of  21  cu.ft.  and  the  machine  can  dredge  to  a  depth  of  35  ft. 
The  dredge  is  propelled  by  two  sets  of  triple-expansion  surface-condens- 
ing engines  of  1250  indicated  horse-power  combined,  driving  twin 
screws,  and  giving  a  speed  of  8  knots  when  the  vessel  is  fully  loaded. 

The  dredge  worked  from  sunrise  to  sunset ;  by  preference  only  dur- 
ing the  summer  months,  but  also  in  winter  when  absolutely  necessary . 

When  dredging  in  soft  clay,  six  loads  per  day  were  generally 
dredged  and  discharged  at  a  distance  of  three  nautical  miles.  The 
daily  time  record 


tj     ItJCUiU     Ueiilg. 

Dredging                     

Perl 
Hrs. 

1 

>oad. 
Min. 
0 

TransDort 

1 

10 

Mooring  and  unmooring               . 

0 

30 

Six  loads  at  2  hours  and  40  minutes.  . 
From  and  to  anchorage.  . 

,.    16 

0 

0 
30 

19       10 


COST  DATA  263 

On  one  occasion  seven  loads  were  removed  during  one  day  of 
17J  hours.  The  shortest  time  consumed  in  filling  the  hopper  was 
55  minutes.  In  dredging  sand  deposit  in  the  channel,  only  four  loads 
per  day  could  be  removed  under  favorable  circumstances ;  the  time 
record  being: 

Per  Load. 

Hrs.  Min. 

Dredging 2  0 

Transport  and  discharge 1  10 

Mooring  and  unmooring 0  30 

Four  loads  at  3  hours  40  minutes 14  40 

Dredger  in  and  out  of  port 1  20 

19      40 

The  success  of  dredging  at  sea  depends  principally  upon  the 
weather^  though  the  "Percy  Sanderson,"  being  of  great  size,  can 
work  in  a  seaway  up  to  3  ft.  high,  when  not  on  the  beam. 


II 

Mr.  Henry  N.  Babcock,  M.  Am.  Soc.  C.  E.,  in  Engineering  News, 
Vol.  LVI,  described  the,  work  of  the  two  hydraulic  hopper  dredges 
"  Manhattan"  and  " Atlantic,"  used  by  the  U.  S.  Government  in 
the  improvement  of  the  Ambrose  Channel,  New  York.  Concern- 
ing the  cost  Mr.  Babcock  says: 

"Before  July  1,  1905,  the  dredges  were  undergoing  considerable 
alterations  and  repairs  to  better  adapt  them  to  dredging  the  channel 
material.  They  had  removed  467,450  cu.yds.  of  material  in  eight 
months'  work  of  one  dredge,  and  two  months'  of  the  other  (total 
ten  months)  at  a  field  cost  of  9.9  cts.  per  yd.,  as  nearly  as  data  at 
hand  show;  some  of  the  earlier  bills  were  not  paid  from  this  office. 

"From  July  1,  1905,  to  May  31,  1906,  eleven  months'  work  for 
each  dredge,  they  took  out  3,258,707  cu.yds.,  at  a  field  cost  of  5.274 
cts.  per  yd.,  the  results  from  the  two  dredges  being  almost  identical. 
This  cost  is  divided  up,  in  reference  to  different  parts  of  the  work 
done,  as  follows: 

Pumping 3.357  cts.  =  63.66% 

Turning, 0 . 206  =     3 . 90 

Going  to  dump 0.835  =    15.83 

Dumping 0. 223  =     4 . 22 

Returning  from  dump 0.653  =    12.39 


5.274  cts.   =    100% 


264 


A  TREATISE   ON  DREDGES   AXD   DREDGING 


"The  getting  of  the  material,  pumping  and  turning,  make  almost 

exactly  two-thirds  the  cost,  and  getting  rid  of  it,  the  other  one-third. 

"Divided  up  according  to  different  items  of  expenditure,  it  is: 


Payroll 1.761  cts. 

Coal 1.408 

Water 0.039 

Subsistence 0 . 476 

Engine-room  supplies 0 . 098 

Miscellaneous  supplies 0. 150 

Repairs  and  renewals 1 . 342 


33.39% 

26.69 

00.75 

9.02 

1.87 

2.84 
25.44 


5. 274  cts.   =100% 

"These  dredges  are  able  sea  boats  and  stay  at  work  in  Ambrose 
Channel  in  stormy  weather,  until  it  gets  too  rough  to  go  to  sea  arid 
dump,  turning  in  the  trough  of  the  waves.  They  cannot  work 
quite  as  fast  in  rough  as  in  still  weather,  because  the  pipes  have  to 
be  lifted  more  frequently  to  prevent  the  ship  riding  over  them. 
When  the  weather  gets  too  thick  to  see  buoys  and  ranges  work 
has  to  be  suspended.  But  the  chief  cause  of  delays  has  been  due 
to  repairing. 

"The  following  table  gives  the  relative  importance  of  the  different 
causes  of  delay  and  lost  time,  being  the  record  of  two  dredges  working 
eleven  months  each,  July  1,  1905,  to  May  31,  1906: 


•" 

Whole 
Days. 

Parts  of  Days 
Hrs.        Mins. 

Total  in 
Days  of 
24  Hours 

Percent- 
age. 

\ctually  at  work 

8041         38 

335    1 

50   0 

Repairing          

112 

628       05 

138  1 

20   6 

Foe  and  snow 

272       40 

11  5 

1    7 

Storm            

6 

177       15 

13  4 

2  0 

Taking  on  coal/etc.,  minor  repairs, 
and  clearing  up  parts  of  Saturdays 

1102       37 

46  0 

6  9 

Miscellaneous 

89       35 

3  7 

0  6 

In  July,    1905,   before  night  work 
be^an                       *       .        .... 

294       00 

12  ° 

1  8 

Sundays  and  holidays 

110 

110  0 

16  4 

670.0 

100 

"The  lost  time  due  to  repairs  is  the  item  which  we  are  trying 
to  reduce  now.  The  value  of  this  time  far  exceeds  the  cash  cost 
of  the  repairs.  During  the  last  three  months  (March  to  May  31, 
1906)  each  dredge  has  averaged  8908  cu.yds.  of  excavation  per  day 


COST  DATA  265 

t 
for  every  day  on  which  it  has  worked  at  all.    At  9  cts.  per  yd.,  the 

price  paid  for  contract  work  in  the  same  channel,  this  amounts  to 
$801  per  day,  and  at  this  per  diem  valuation  the  value  of  time  lost 
by  reason  of  repairs  in  eleven  months  as  above  is  $110,538,  while 
the  money  actually  paid  for  these  repairs  was  $43,721. 

ESTIMATES  OF  EXPENSES 

"In  September,  1905,  a  preliminary  estimate  was  made  of  the 
total  expenses  which  each  dredge  would  have  to  meet  and  pay  for 
out  of  the  results  of  the  work,  if  operated  by  a  contractor.  This 
estimate,  $12,500  per  month,  has  proved  so  nearly  accurate  that  no 
general  revision  of  it  has  yet  been  made.  It  is  as  follows : 

MONTHLY  OPERATING   EXPENSES 

Payroll $2,660 

Coal 2,480 

Water 60 

Subsistence 700 

Engine-room  supplies 150 

Other  supplies 250 

Casual  repairs ^  .  500 


Total  per  month $6,800 

ANNUAL  CARE   OF   PLANT 

Docking  and  painting,  twice  a  year $1,250 

Renewals  of  equipment 12,150 

Miscellaneous 1,000 


Total  per  year $14,400 

Average  per  month 1,200 

ANNUAL  FIXED  CHARGES  UPON  ORIGINAL  COST, 
ESTIMATED  AT  $341,800 

Sinking  fund,  toward  original  cost,  10% $34,180 

Interest,  at  4% 13,672 

Insurance  risk,  2% 6,836 

Fixed  charges  per  year $54,688 

Average  of  fixed  charges,  per  month 4,500 

Total,  per  month $12,500 

"  The  sinking  fund  is  meant  to  cover  depreciation.  The  insurance 
covers  risk  only,  not  what  would  be  actual  cost.  For  steel  boats  not 
going  more  than  five  miles  from  harbor,  it  probably  more  than  covers 
any  risk  incurred.  To  meet  these  charges  out  of  excavations  which 
would  otherwise  be  made  under  contract  at  9  cts.  per  yd.  requires  an 
average  output  for  each  dredge  of  138,900  cu.yds.  per  month— 277,800 


266  A   TREATISE    ON    DREDGES   AND  DREDGING 

cu.yds.  for  the  two  dredges.     Any  excess  over  this,  a  contractor 
would  apply  to  expenses  of  administration  and  to  dividends. 

"  The  twelve  months  ending  June  30,  1906,  show  a  monthly  aver- 
age, for  the  two  dredges,  of  316,200  yds.;  the  last  three  months' 
average  is  458,319  yds.;  in  the  last  month,  June,  1906,  535,692  yds. 
were  excavated.  The  work  of  June,  1906,  is  the  largest  month's 
work  which  this  plant  has  yet  done.  Under  favorable  conditions 
as  to  kind  of  material  and  with  little  lost  time  due  to  repairs,  etc., 
it  may  perhaps  be  exceeded,  but  it  is  doubtful  whether  the  plant 
can  permanently  maintain  so  high  an  average." 

COST  OF   HYDRAULIC  DREDGING,   HARBOR  OF  WILMINGTON,   CAL. 

In  the  harbor  improvements  at  San  Pedro  and  Wilmington,  Cal. 
a  suction  dredge  built  by  the  Ellicott  Machine  Co.,  of  Baltimore, 
Md.,  is  employed.  Prior  to  the  acceptance  of  the  same  by  the 
United  States,  and  during  an  efficiency  test,  16,450  cu.yds.  of  material 
were  removed  from  the  proposed  harbor  and  deposited  behind  a 
bulkhead.  The  total  cost  for  labor  employed,  including  superintend- 
ence, and  for  the  fuel,  water  and  other  supplies  expended  on  account 
of  this  work,  was  $1682.46,  or  at  an  average  cost  of  10.2  cents  per 
cu.yd.  of  material  handled.  The  dredge  was  placed  in  commission 
April  1,  1905,  and  between  this  date  and  June  30,  1905,  it  removed 
227,464  cu.yds.  of  material,  which  consisted  principally  of  sand 
intermingled  with  shell,  and  a  small  percentage  of  clay,  cobbles, 
disintegrated  sandstone  and  very  compact  and  hard  mud.  During 
the  period  mentioned  the  dredge  was  laid  up  16  days,  May  15  to 
30,  1905,  so  that  the  actual  working  time  was  2J  months,  the 
average  rate  of  dredging  per  month  being  thus  91,000  cu.yds. 

The  following  statement  shows  the  cost  of  the  dredging  during 
;bhe  period  from  April  1  to  June  30,  1905: 

Routine  office  work,  labor $673 . 33 

Care  of  plant  and  property,  labor 180 . 00 

Surveys,  labor  and  supplies 155 . 63 

Towing  and  dispatch  work,  labor,  fuel  and  supplies 316 . 00 

Alterations  and  repairs  to  dredging  plant,  labor,  and 

material 2,432 . 52 

Operating  dredge,  including  superintendence  and  labor 
charges,  fuel,  fresh  water,  lubricants,  and  all  other 

supplies 10,084 . 54 

Deterioration  of  plant  and  property,  estimated 2,263 . 94 


$16,105.96 
Cost  per  cubic  yard,  $0.0708. 


COST  DATA  267 

In  addition  to  the  hydraulic  dredge,  the  following  auxiliary 
floating  plant  is  employed:  A  gasoline  launch,  length  over  all  30  ft. 
1J  in.,  7  ft.  beam,  depth  3  ft.  3  in.,  propelled  by  a  16  H.P.  "standard  " 
engine.  Also  9  pontoons,  each  35X10X3  ft.;  15  pontoons,  each  21 
ft.  3  in.  X 10  X3  ft.;  1  water  boat,  34  ft.  9  in.  X10  ft.  X4  ft.  6  in.;  1 
oil  boat,  34  ft.  9  in.  X10  ft.X4  ft.  6  in.;  1  derrick  boat,  29  ft.  6  in.X 
10ft.  7  in.X 3  ft.  10  in. 

The  original  cost  of  the  dredging  plant  was  as  follows: 

20-inch  suction  dredge $99,453 

Gasoline  launch 1,733 

Discharge  pipe  line  for  dredge 3,023 

Rubber  sleeves 1,275 

Pontoons  and  barges 6,501 

Skiffs 154 


III 

The  following  example  illustrates  the  cost  of  dredging  with 
dipper  dredges  of  small  capacity: 

Capt.  Frederick  V.  Abbot,  Corps  of  Engineers,  U.  S.  A.,  while  in 
charge  of  the  improvement  of  the  harbor  of  Charleston,  S.  C.,  thus 
described  the  cost  of  the  work  of  the  dredge  "  Santee."  The  machine 
was  built  by  the  Osgood  Dredge  Co.  of  Albany,  N.  Y.,  with  a  boom 
50  ft.  long  and  the  dipper  of  1}  cu.yds.  capacity. 

"  In  regard  to  the  cost  of  the  work,  I  quote  the  following  figures : 
Work  began  November  21,  1893. 

November 5,572  cu.yds.  mud,      7  stumps  cost  $512.        Average  7    cts. 

December 15,721  cu.yds.  mud,  220      " 

January. 13,628  cu.yds.  mud,  628      " 

February 12,000  cu.yds.  mud,    53      " 

March 29,996  cu.yds.  mud,  138      " 

April 14,313  cu.yds.  mud,  " 


690.  4 

456.  "  3 

945.  "  8 

470.  "  1 

265.  "  2 


"Work  was  suspended  April  30,  1894.  The  total  result  of  the 
work  is  as  follows : 

"Six  thousand  and  seventy-five  linear  feet  of  canal  have  been 
completed  between  50  and  60  ft.  wide  and  between  6  and  7  ft.  deep 
at  low  water,  through  the  marsh,  which  is  between  4  and  5  ft.  above 
low-water  level.  The  material  consisted  largely  of  exceedingly 
hard  and  sticky  blue  clay  in  which  large  cypress  stumps  were  bedded. 

"The  material  was  harder  than  any  I  have  encountered  any- 
where else  in  the  district,  and  could  not  be  handled  at  all  by  a  clam- 


268  A  TREATISE   ON   DREDGES    AND   DREDGING 

shell  machine.  The  total  number  of  cubic  yards  •  excavated  was 
91,230,  which  included  793  stumps  and  three  large  logs.  The  average 
cost  for  the  half  year  including  all  repairs  and  every  expense  properly 
chargeable  to  dredging,  but  making  no  allowance  for  depreciation 
of  plant,  is  between  3  and  4  cts.,  or  about  one-tenth  of  the  lowest 
contract  price  (.35^)  that  I  have  ever  paid  for  work  in  this  locality. 

"  The  machine  is  now  in  thoroughly  good  order,  and  I  see  no 
reason  why  it  could  not  run  six  months  longer  without  any  general 
overhauling. 

"In  soft  material  the  capacity  is  fully  2000  yds.  a  day,  and  we 
have  exceeded  1500  yds.  on  several  occasions,  when  the  proportion 
of  stiff  clay  to  the  ordinary  marsh  mud  was  not  excessive;  the 
stumps  seemed  to  offer  no  resistance  to  her  work,  as  she  generally 
pulled  the  bucket  right  up  through  them,  splintering  the  solid  wood 
so  much  that  they  would  fall  through  the  bucket.  On  one  or  two 
occasions  when  we  unfortunately  brought  the  whole  stump  out  it 
stuck  in  the  bucket  and  gave  some  trouble.  The  greater  portion 
of  the  delay  was  caused  by  excessive  stickiness  of  the  clay,  which 
would  remain  in  the  bucket  sometimes  several  minutes  after  the 
bottom  door  was  opened  before  it  would  fall  through. " 

The  amount  of  work  together  with  a  detailed  report  of  the  sup- 
plies consumed  during  a  month  by  the  dipper  dredge  "  Alpha, " 
of  1  cu.yd.  capacity  while  working  on  the  Raritan  River  was  given 
by  Mr.  E.  L.  Sugram  as  follows: 

"  During  the  month  of  September,  1889,  the  U.  S.  Dredge  'Alpha ' 
has  been  working  in  the  Raritan  River,  making  a  10-ft.  channel 
out  of  a  7-ft.  one.  The  material  removed  is  light  shale  and  gravel. 
The  actual  time  worked  was  207  hrs.,  and  the  amount  dredged  12,050 
cu.yds.  The  best  day's  work  was  750  cu.yds.,  and  the  worst  300 
cu.yds.  The  machine  is  not  worked  very  hard  on  account  of  an 
insufficient  number  of  scows  in  the  plant.  The  following  supplies 
have  been  consumed  during  the  month: 

Line 350  Ibs. 

Lard  oil 12^  gals. 

Black  oil 13  gals. 

Cylinder  oil 14£  gals. 

Grease 119  Ibs. 

Cotton  waste 8$-  Ibs. 

Coal .  4 1J  tons 

Water 66,500  gals. 

Kerosene 12^  gals. 


COST   DATA 


269 


"The  cost  for  repairs  has  been  almost  nothing. 

"  The  entire  cost  of  running  the  whole  plant,  including  interest 
on  valuation,  for  the  month  of  September  last  was  approximately 
$1400." 

The  work  of  the  dipper  dredge  No.  4  of  the  Atlantic  and  Gulf 
Coast  Canal  and  Okeechobee  Land  Co.  is  taken  from  the  official 
report  for  the  month  of  April,  1890.  The  machine  was  built  by 
the  Osgood  Dredge  Co.,  of  Albany,  N.  Y.;  the  hull  was  90X35X9 
ft.  with  spuds  20X20  in.  The  boom  was  50  ft.  long  and  the  dipper 
of  3}  cu.yds.  capacity. 

LOG   OF  DREDGE   No.  4,  FOR  MONTH   OF  APRIL,  1890 


Days  worked  (12  hours) 21 

Number  of  crew 6 

Length  of  cut,  in  feet 2,747 

Width  of  cut,  in  feet  (average) .  50 

Depth  of  cut,  in  feet  (average) .  1 1 

Cubic  yards  dug  in  month ....  55,957 

Average  per  day 2,664 

Maximum  per  day 3,809 


Fuel,  62  cords  wood $124.00 

Payroll 239.66 

Provisions 59 . 11 

Supplies 33 . 49 

Repairs 46 . 17 

Freight 13.02 

Incidentals..  35.90 


Total  cost  for  month $551 . 35 


Cost  per  cubic  yard 0.99  of  1  cent. 

Material:     Cypress  swamp,  muck,  and  sand  with  rock  at  bottom  of  cut. 


IV 

The  cost  of  deep-water  dredging  with  a  clamshell  dredge  for 
the  Stony  Point  extension  of  the  Buffalo,  N.  Y.,  Breakwater,  was 
given  by  Mr.  Emile  Low,  M.  Am.  Soc.  C.  E.,  in  Engineering  News, 
of  October  11,  1906: 

"It  may  be  of  interest  to  the  profession  to  state  the  cost  of  the 
deep-water  dredging  with  a  very  large  clamshell  dredge  which 
was  done  some  years  ago  on  the  Stony  Point  extension  of  the  Buffalo, 
N.  Y.,  breakwater. 

"The  extension  consists  of  two  breakwaters,  one  9989  ft.  long 
and  the  other  2803  ft.  long.  The  longer  structure  is  made  up  of 
two  parts,  the  rubble  mound  section  (stone  breakwater),  7250  ft. 
long,  and  the  timber  crib  section  (South  Harbor  section),  2739 
ft.  long. 

"  The  Stony  Point   timber-crib  breakwater,  with   the   exception 
of  a  few  hundred  feet  next  the  shore,  stands  upon  an  artificial  founda- 


270  A  TREATISE   ON  DREDGES   AND  DREDGING 

tion  of  sand  and  gravel,  up  to  the  level  of  the  original  lake  bottom, 
this  material  having  been  back  filled  into  a  trench  dredged  practically 
to  bed  rock.  At  the  outer  end  of  the  breakwater,  where  the  water 
is  over  22  ft.  deep  (also  the  maximum  depth  of  the  timber  cribs), 
a  rubble  stone  foundation  is  interposed  between  the  bottom  of  the 
cribs  and  the  top  of  the  gravel  rilling. 

"The  South  Harbor  timber  breakwater  also  stands  upon  a  similar 
artificial  foundation,  with  the  exception  that  the  rubble  stone 
foundation  is  almost  uniformly  8  ft.  high,  the  cribs  resting  directly 
upon  this. 

"Under  the  original  specifications  contractors  were  permitted 
to  use  either  hydraulic  dredges  or  the  clamshell  type. 

"The  successful  contractors,  Hughes  Bros.  &  Bangs,  elected  to 
excavate  the  trenches  by  means  of  a  very  large  clamshell  dredge, 
built  expressly  for  this  work  by  the  Osgood  Dredge  Co.,  of  Albany, 
N.  Y. 

''This  dredge  was  illustrated  and  fully  described  in  Engineering 
News  of  February  2,  1899,  while  it  was  engaged  on  the  Buffalo  works. 
It  may  be  noted  here  that  the  clamshell  bucket  of  this  dredge 
has  a  capacity  of  10  cu.yds.  and  weighed  empty  over  30,000  Ibs. 
The  hull  of  the  dredge  is  120  ft.  long  and  40  ft.  broad.,  and  a 
false  stern  increases  the  total  length  to  151  ft.  The  dredge  had 
to  excavate  material  from  depths  up  to  70  ft.,  much  of  it 
solidly  compacted.  Most  of  the  material  dredged  was  a  moderately 
stiff  red  clay,  mixed  with  some  blue  clay.  Overlying  this  clay 
was  a  layer  of  sand,  perhaps  one  or  two  feet  thick.  Underlying 
the  clay  next  to  the  rock  was  a  layer  of  hard  blue  clay,  mixed 
with  broken  stone  or  gravel,  and  in  places  there  were  a  good 
many  large  boulders. 

"The  dredged  material  was  generally  transported  to  a  dumping 
ground  10,000  ft.  distant  from  the  dredge,  the  time  for  the  round 
trip  being  1  hour  and  6  minutes.  Three  steel  scows  were  used  to 
transport  the  excavated  material. 

"The  principal  cause  of  delay  was  the  sea  and  wind  (about  three- 
eighths  of  the  total  delays).  Considerable  delay  was  also  due  to 
the  clamshell  bucket.  Moving  and  placing  the  dredge  was  another 
large  item  of  delay. 

"Generally  the  dredge  lay  at  anchor,  in  working  position,  through- 
out the  week,  and  on  Sundays  was  towed  to  shelter  behind  the  com- 
pleted Stony  Point  breakwater.  'This  was  also  done  during  storms. 


COST  DATA 


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272  A  TREATISE   ON  DREDGES  AND  DREDGING 

Later  in  the  season,  in  the  fall  of  the  year,  the  dredge  was  towed 
to  shelter  behind  the  partially  completed  South  Harbor  breakwater 
every  night. 

"The  daily  routine  of  the  dredge  was  as  follows:  Men  rise  at 
4.30  A.M.;  dredge  begins  work  at  5;  breakfast,  6  to  6.30;  dinner 
12  to  12,30  P.M.;  supper  after  finishing  work,  at  7  P.M. 

ESTIMATE  OF  COST  OF  DREDGING 

"The  cost  of  operations  for  the  season,  commencing  with  May 
5,  1899,  and  ending  October  16,  1899,  is  given  below  in  detail. 

"  During  this  period  316,343  cu.yds.  of  material,  scow  measure, 
was  dredged.  The  place  measure  was  286,335  cu.yds.,  showing 
an  increase  of  30,008  cu.yds.  by  scow  measurement,  or  10.48  per 
cent. 

"  The  monthly  expense  of  operating  the  dredge  is  shown  below: 

1  runner , $90 . 00 

1  second  runner 35 . 00 

1  fireman 35 . 00 

1  deckhand 35.00 

1  greaser 30 . 00 

1  watchman 30. 00 

7  deckhands,  at  $30.00. ..." 2K) .  00 

1  cook 30.00 

1  cook's  helper 15 . 00 


$510.00 

11  For  working  overtime  the  men  received  15  cts.  per  hour;  the 
runner  30  cts.  per  hour.  The  supplies  for  board  cost  $12  per  month 
per  man. 

"  As  the  superintendent  had  charge  of  both  the  dredging  and 
gravel  filling,  one-half  his  wages,  or  $62.50  per  month,  is  charged  to 
dredging. 

"  The  cost  of  the  fuel  was  52J  cts.  for  every  100  cu.yds.  of 
material  excavated. 

"  To  keep  the  dredge  and  scows  free  from  water,  an  old  dredge 
was  rigged  up  with  a  steam  siphon,  the  cost  of  which  per  month  was: 

One  man,  per  month $40 . 00 

Coal,  20  tons,  at  $1.50 30.00 


$70.00 


COST  DATA  273 

"  Other  expenses  were  as  follows: 

New  cables  (steel) $100  per  month 

Oil,  dope,  waste,  etc 20 

Blacksmith  shop 175 

Lines,  cables,  etc.  (hemp) 40 

Miscellaneous  expenses 50 

Yard  expenses 100 

"  Range  piles  and  buoys  cost  $256  for  the  season. 

Small  tugs,  coaled $20  per  day 

Large  tugs,  coaled 25      " 

Larger  tugs,  coaled '. .       30      " 

"  The  assumed  value  of  the  plant  is  as  follows: 

Clamshell  dredge,  "Fin  MacCool" $60,000 

Steel  dump  scow,  "  Protective  Policy  " 12,000 

Steel  dump  scow,  "  Gold  Standard  " 10.000 

Steel  dump  scow,  " Cuba  Libre " 10,000 


Total $92,000 

Annual  depreciation,  10% 9,200 

Annual  interest,  6% 5,520 


Total ,$14,720 

"Total  expenses  for  the  season  of  1899: 

Superintendence $329 . 67 

Wages 2,823. 14 

Board 980.34 

Coal 1,660.80 

Towing,  tug  hire 5,830 . 00 

Siphoning 369 . 24 

Cables,  main,  steel 527 .49 

Lines,  ropes,  etc.,  hemp 210.99 

Blacksmith  shop 923. 11 

Yard  expenses 527.49 

Miscellaneous  expenses •   263 . 74 

Range  piles  and  buoys 256 . 00 


Total $14,702.01 

Depreciation  and  interest 14,720. 00 


Total $29,422.01 

Cubic  yards  excavated 316,343 

Cost  per  cubic  yard 316343    =$0-0930/ioo 

$14,702.01 
Operating  expenses QIAQAQ    =S0.0464/ 


316,343 


/ico 


$14.720.00 
Depreciation  and  interest 316  343    =      '        //1QO 


274  A  TREATISE  ON   DREDGES  AND  DREDGING 

"  The  price  paid  the  contractor  was  18  cts.  per  cu.yd.,  amounting 
to  $56,941.74.  Soon  after  the  completion  of  this  work  this  dredge 
was  towed  (in  the  fall  of  1899)  to  Long  Island  Sound,  via  the  Wei- 
land  Canal  and  St.  Lawrence  River.  After  working  here  a  short 
time,  the  dredge  was  transferred  to  the  improvement  of  Baj^  Ridge 
and  Red  Hook  Channels,  New  York  Harbor,  for  which  work  Hughes 
Bros.  &  Bangs  are  the  contractors." 


INDEX 


Agitators,  95 

Allen's  scraper,  96 

American  grab  dredges,  168 

American  dumping  scows,  193 

Annual  expenses,  258 

Apjohn,  James  H.,  96 

Arnold,  W.  H.,  181 

Arnold  clamshell  bucket,  182 

Austin  drainage  excavator,  247 

Automatic  devices  for  soundings,  1,  3 

Babcock,  Henry  N.,  19,  263 
Barges,  190 

deck,  192 

open-hold,  190 

steel-decked,  238 
Bates,  Lindon  W.,  99 
Belt  conveyor,  88,  185 
Bishop  conical  screws,  143 
Blasting: 

at  Hell  Gate,  N.  Y.,  42 

at  Henderson's  Point,  46 

on  the  Erie  harbor,  30 

on  the  Rhine  River,  29 

on  the  Severn  River,  29 
Boilers,  80,  115,  123,  130,  163,  181 
Boom,  163,  169 
Buckets: 

Arnold  for  clamshell  dredges,  182 

clamshell,  173 

of  dipper  dredge,  155 

elevator,  198 

for  ladder  dredges,  70 

for  land  excavation,  246 

orange-peel,  174 

for  placer  dredges,  220 

Caissons  for  rock  excavation,  34 
Centrifugal  pump,  98 


Centrifugal  pump  lining,  99 

runner,  124 

shell,  98,  119,  129 
Chutes,  71,  186,  200 
Clamshell  dredges,  62,  173 

"Champion,"  181 

"FinnMacCool,"  178 
Clay  and  loam,  8 

Comparison  of  methods  of  sounding,  13 
Comparison  of  rockbreaking  and  blast  - 

'ing,  39 
Compressed  air  for  clamshell  bucket, 

181 

Compressed  air  fof  dredging,  147 
Conglomerate,  6 
Contractors'  profit,  259 
Conveyor  belt,  88,  185 
Conveyor  pipe,  100,  185 
Cost  of: 

blasting  rock,  37-41 

operating  dredges,  253 

dredging  Ambrose  Channel,  263 

deep  dredging  at  Buffalo,  269 

dredging  clamshell  dredge,  269 

dredging  harbor  of  Wilmington,  Cal., 
266 

dredging  ladder  dredges,  261-267 

dredging  Salina  Harbor,  261 

dredging  on  St.  Lawrence  River,  212 

gold  dredging,  232 

hydraulic  dredging,  263-266 

repairing,  209,  256 

rock  blasting  at  Hell  Gate,  46 

rock-breaking,  39 

rock  excavation,  37 
Coupling  for  discharge  pipe,  150,  189 
Crews,  56,  93,  210,  230,  272 
Cutters,  96 

of  Lobnitz  machine,  25 
275 


276 


INDEX 


Deck  barges,  192 
'  Deck  scows,  191 
Delays  in  dredging,  256 
Diamond  dredging,  217 
Dipper,  155 

Dipper  dredges,  4,  61,  150 
output  of,  157 
"Alpha,"  158 
"Chicago,"  151-158 
"  Frontenac,"  158 
"  Independent,"  161 
"Majestic,"  164 
Dipper  handle,  155 
Disintegrated  rock,  6 
Ditcher: 

Junkin's,  250 
Mayer's,  251 
Stephen's,  248 
Double-chain    attachment     for    grab 

bucket,  176 

Double-ladder  floating  elevator,  201 
Drag,  207 

Drainage  excavator,  247 
Dredge : 

"Alpha,"  158 
"Baldwin,"  207-213 
"Cadiz,"  83 
"Caffrey,"  142 
"Champion,"  181 
"Chicago,"  151-158 
"City  of  Paris,"  91 
"City  of  Rouen,"  116 
"Delta,"  123 
"Essayon,"  144 
"  Finn  MacCool,"  178 
"Francis  T.  Simmons,"  67 
"Frontenac,"  158 
"Galveston,"  67,  210 
"Hunter,"  228 
"Independent,"  161 
"  J.  Israel  Tarte,"  67,  120,  208 
"King  Henry  VII,"  125 
"Lady  Aberdeen,"  208 
"LadyMinto,"  213 
"La  Fontaine,"  207,  213 
"Laurier,"  207,  213 
'  "Laval,"  213 


Dredge : 

"Leviathan,"  67 

"Majestic,"  164 

"Marne,"  84 

"McAlester,"  144 

"Montana,"  142 

"Montevideo,"  137 

"Nereus,"  107 

"  Pas-de-Calias,"  79 

"Percy  Sanderson,"  262 

"St.  Petersburg,"  133 

"Thomas,"  114 

"Ville  de  Rochefort,"  75 
Dredges: 

'  'Atlantic  "  and  "  Manhattan, "  67, 263 
clamshell,  62,  173,  178 
dipper,  4,  61,  150 
electric,  227 
grapple,  62,  173 
high-tower  ladder,  89 
hydraulic,  4,  51,  94,  234 
ladder,  3,  52,  60,  219 
non-propelling,  61 
orange-peel  bucket,  62,  174 
pneumatic,  4,  61,  147 
sea-going,  63,  74 
self-propelling,  61,  85 
semi-sea-going,  83 
stirring,  4,  61,  140 
universal,  132 
Dredging  for: 
diamond,  217 
filling  low  lands,  240 
gold,  218 

industrial  purposes,  233 
metals,  217 
platinum,  217 
sand  and  gravel,  233 
tin,  217 
Dredgmen,  56 
Drilling  boat: 
"Ingersoll,"  33 
"Rand,"  34 
used  at  Iron  Gates,  32 
at  New  York,  31 
on  the  Rhine  River,  35 
Dumping  scows,  192 

with  sliding  platform,  196 


INDEX 


277 


Efficiency: 

of  rockcutters,  23,  27 
pumps,  101 

Electric  dredges,  227 

Elevator,  double-ladder  floating,  201 

floating,  200 
Elevator  on  land,  198 
Employment  of  dredges,  2 
Endless  chain,  70 
Engines: 

for  dipper  dredges,  156,  162 

for  grab  dredges,  179 

hydraulic  dredge,  114,  124,  128 

ladder  dredge,  78,  82,  88,  92 

for  spuds,  166 

of  universal  dredges,  134,  138 
English  grab  dredges,  169 
Expenses: 

annual,  258 

general,  259 

running,  254 
Exploding  batteries,  35 
Explosives,  45,  48 
Estimating  dredged  materials,  16 

Fairbanks'  walking  dredge,  249 
Filling: 

for  extending  Governor's  Island,  X. 
Y.,  243 

for  improving  Long  Beach,  L.  I.,  243 

marsh  lands,  240 

tide  water  lands  at  Seattle,  241 
Floating  clough,  141 
Floating  elevator,  200 

with  double  ladder,  201 
Flood  rock,  Hell  Gate,  N.  Y.,  42 
Flow  of  debris  through  pipes,  71,  186 
Forward  feeding  hydraulic  dredge,  104, 

123 
Friction  in  pipes,  102 

Gaging  the  draft  of  scows,  16 
Gold  dredging,  218 
Grab  bucket: 

for  clay,  173 

for  gravel  and  boulder,  173 

for  mud  and  silt,  173 


Grab  bucket: 

for  unloading  barges,  202 
Grab  dredges: 

American,  168 

double-line  attachment,  176 

English,  169 

single-chain  attachment,  175 

South  American,  172 
Graduated  rods  for  soundings,  12 
Grapple  dredges,  62,  173 
Gravel,  7 

dredging,  236 

Hammering  rocks,  22 
Handling  of  debris,  54 

sand,  237 
Hardpan,  8 

Harrow  and  scrapers,  141 
High-tower  ladder  dredges,  89 
Honeycombing  the  reef,  43 
Hopper  dredge: 

"City  of  Rouen,"  116 

"Montevideo,"  137 

"Pas-de-Calais,"  79 

"Percy  Sanderson,"  262 

"Thomas,"  114 
Hopper  for  debris,  81,  106 
Hopper  steamer,  195 
Hull  of  dredges,  68,  77,  85,  117,  126, 

134,  151,  165,  179 
Hydraulic  dredges,  4,  51,  94,  234 

"Atlantic"   and   "Manhattan,"    67, 
263 

forward  feeding,  104,  123 

lateral  feeding,  104,  120 

radial  feeding,  104,  125 

sea-going,  110 

"City  of  Rouen,"  116 

"Delta,"  123 

"Galveston,"  67,  210 

"  J.  Israel  Tarte,"  67,  120,  208 

"King  Edward  VII,"  125 

"Leviathan,"  67 

"Nereus,"  107 

"Thomas,"  114 
Hydraulic  jets,  97 
Hydraulic  survey,  14 
Hydro-penumatic  dredges,  148 


278 


INDEX 


Increase  of  material,  18  , 

Industrial  dredging,  233 
Ingersoll  drilling  boat,  33 
Insurance,  259 
Interest  on  capital,  258 

Jandin,  M.,  147 
Jets  of  compressed  air,  149 
Jets  of  water,  97,  144 
Junkin's  ditcher,  250 

Ladder  dredges,  3,  52,  60,  219 

"Cadiz,"  83 

"City  of  Paris,"  91 

"Pas-de-Calais,"  79 

"Percy  Sanderson,"  262 

"ViUe  de  Rochefort,"  75 
Land  dredging,  246 
Lateral  feeding  hydraulic  dredge,  104, 

120 

Launches,  59 

Lead  line  for  soundings,  12 
Lift  holes,  46 
Light  on  dredges,  50 
Loam  and  clay,  8 
Lobnitz  rock  cutter,  24 

Mayer's  ditching  machine,  251 
Mann,  L.  M.,  87 

McAlester,  M.  D.,  Maj.  U.  S.  A.,  144 
McDerby,  George  C.,  U.  S.  A.,  42 
Measurement  of  quantities,  15 

by  gaging  the  draft  of  scows,  16 

in  place,  16 

by  scows,  16 
Meyer,  Cornelius,  v 
Mineral  dredging,  217 
Mud  or  silt,  10,  187 

Newton,  Gen.  John,  U.  S.  A.,  42 
Non-propelling  dredges,  61 

Ocherson,  J.  A.,  141 
Open-hold  barges,  190 
Operating  expenses,  254 
Operations  for  hydraulic  survey,  12 
Orange-peel  bucket  dredges,  62,  174 


Pardessus,  R.  M.,  13 
Pipe: 

conveyors,  100,  185 

discharging,  100 

floating,  185 

suction,  95 

Placer  dredge,  220 

with  revolving  screens,  222 

with  shaking  screens,  224 

with  sluice-box,  225 
Place  measurement,  16 
Platinum  dredging,  217 
Pneumatic  dredges,  4,  61,  147 
Pontoons,  191 
Profit  of  contractors,  259 
Propelling  machines,  77,  82,  84,   109, 

119,  171 

Propellers  for  stirring,  143 
Power  for  ladder  dredge,  72 
Power  required  for  pumps,  102 
Pump  lining,  99 
Pump  shell,  98,  119,  129 

Rackrock,  35 

Radial  feeding  hydraulic  dredge,  104, 

125 

Rand  drilling  boat,  34 
Revolving  drums  for  stirring,  145 
Revolving  screens,  222 
Revolving  wheels  for  stirring,  143 
Ridgway  belt  conveyor,  88 
Robinson,  A.  W.,  19,  64,  104 
Rock,  6 

disintegrated,  6 

dredging,  40 
Rock-cutter: 

Lobnitz,  24 

Scott  &  Godsir,  23 
Rock  excavation: 

honeycombing  the  reef,  43 

lift  holes,  46 

single  large  blast,  42 
Runner  for  centrifugal  pump,  124 

Sand,  9,  186 

Sand  and  gravel  dredging,  233 

Scrapers,  96,  144 


INDEX 


279 


Screw-propelled  tugboat,  198 
Scott  &  Godsir  rock-cutter,  23 
Scow  measurement,  16 
Sea-going  dredges,  63,  74 
Sea-going  hydraulic  dredge,  105 
Sea-going  steam-hopper,  195 
Selection  of  dredges,  50 
Self-propelling  dredges,  61-85 
Semi-sea-going  dredges,  83 
Shaking  screens,  224 
Shrinkage  of  material,  18 
Side-wheeled  tugboat,  198 
Silt  or  mud,  10,  187 
Sinking  fund,  258 

Single-chain    attachment     for     grab- 
buckets,  175 
Sluice  boxes,  225 
Soils,  6 

clay  and  loam,  8 

disintegrated   rock  and   conglomer- 
ate, 6 

hardpan,  8 

gravel,  7 

mud  or  silt,  10,  187 

rock,  6 

sand',  9,  186 
Soundings,  12 

automatic  devices,  13 

graduated  rods,  12 

lead  line,  12 

Pardessus'  method,  13 
South  American  grab  dredge,  172 
Speed  of  pumps,  101 
Sprocket  wheels  for  propulsion,  8 
Spuds,  85,  166,  179 
Stationary  ladder  dredges,  85 
Steam  crane,  82,  135 
Steam  punch,  24 
Steam  hopper,  195 
Steamer: 

"  Henry  Burden,"  110 

"Wiggins,"  143 
Steel  ram,  24 
Stephen's  ditcher,  248 
Stirring: 

by  harrow  and  scrapers,  141 

by  propellers,  143 

by  revolving  drums,  145 


Stirring : 

by  revolving  wheels,  143 

by  water  jets,  144 
Stirring  dredges,  4,  61,  140 

"Caffrey,"  142 

"Essayon,"  144 

"McAlester,"  144 

"Montana,"  142 
Stone-lifters,  53 
Suction  pipe,  95,  149 

connections,  95,  129 
Survey  along  a  determined  course,  15 

by  three  points,  14 

by  triangulation,  14 

Tin  dredging,  217 
Tower  of  ladder  dredge,  70 
Transportation  of  debris,  4 
Tugboats,  58 

sidewheeled,  198 

screw-propelled,  198 
Tumbler,  69 

Universal  dredges,  132 

"Montevideo,"  137 

"St.  Petersburg,"  133 
Unloading    barges     by   double-ladder 
floating  elevator,  201 

by  floating  elevator,  200 

barges  by  grab  bucket,  202 

barges  by  land  elevator,  198 

de"bris  from  hoppers,  106 

machinery,  239 

sand,  239 

Veranteus,  V 

Wages,  210-230 

of  crew  on  electric  placer  dredge,  230 
on  a  hydraulic  dredge,  211 
on  a  ladder  dredge,  210. 
Walking  dredge,  249 
Water  jets,  97,  144 
Watt,  James,  vi 
Work  of  a  ladder  dredge  at  Fox  River, 

Wis.,  87 

dredges  on  St.  Lawrence  River,  204 

hydraulic  dredges,  109-115 


D.  VAN    NOSTRAND    COMPANY 

23  MURRAY   AND  27  WARREN   STREETS 

New  York 

SHORT=TITLE  CATALOG 

OF 


OF 


SCIENTIFIC  AND  ENGINEERING 

BOOKS 


This  list  includes   the  technical  publications  of  the  following 
English  publishers: 

SCOTT,    GREENWOOD   &   CO.         CROSBY   LOCKWOOD   &   SON 

CONSTABLE  &  COMPANY,  Ltd.     TECHNICAL  PUBLISHING  CO. 

ELECTRICIAN  PRINTING   &   PUBLISHING   CO. 

for  whom  D.  Van  Nostrand  Company  are  American  agents. 


JANUARY,  1912 

SHORT-TITLE  CATALOG 

OF  THE 

Publications   and   Importations 

OF 

D.  VAN  NOSTRAND  COMPANY 

23    MURRAY   AND   27    WARREN    STREETS,    N.    Y. 

P 'rices  marked  with  an  asterisk  (*)  are  NET. 
All  bindings  are  in  cloth  unless  otherwise  noted. 


ABC  Code.     (See  Clausen-Thue.) 

Abbott,  A.  V.     The  Electrical  Transmission  of  Energy. 8vo,  *$5  oo 

A  Treatise  on  Fuel.     (Science  Series  No.  9.) i6mo,  o  50 

Testing  Machines.     (Science  Series  No.  74.) i6mo,  o  50 

Adam,  P.     Practical  Bookbinding.     Trans,  by  T.  E.  Maw i2mo,  *2  50 

Adams,  H.  C      Sewage  of  Sea  Coast  Towns 8vo,  *2  oo 

Adams,  H.    Theory  and  Practice  in  Designing 8vo  (In  Press.) 

Adams,  J.  W.     Sewers  and  Drains  for  Populous  Districts 8vo,  2  50 

Addyman,  F.  T.     Practical  X-Ray  Work , 8vo,  *4  oo 

A i  Code.     (See  Clausen-Thue.) 

Aikman,  C.  M.    Manures  and  the  Principles  of  Manuring 8vo,  2  50 

Aitken,  W.    Manual  of  the  Telephone.    Two  Volumes 

d'Albe,  E.  E.  F.,   Contemporary  Chemistry i2mo,  *i  25 

Alexander,  J.  H.     Elementary  Electrical  Engineering i2mo,  2  oo 

—  Universal  Dictionary  of  Weights  and  Measures 8vo,  3  50 

"  Alfrec."    Wireless  Telegraph  Designs 

Allan,  W.     Strength  of  Beams  Under  Transverse  Loads.     (Science  Series 

No.  19.) i6mo,  o  50 

-  Theory  of  Arches.     (Science  Series  No.  1 1.) i6mo, 

Allen,  H.     Modern  Power  Gas  Producer  Practice  and  Applications..  12010,  *2  50 

—  Gas  and  Oil  Engines 8vo,  *4  50 

Anderson,  F.  A.     Boiler  Feed  Water 8vo,  *2  50 

Anderson,  Capt.  G.  L.     Handbook  for  the  Use  of  Electricians 8vo,  3  oo 

Anderson,  J.  W.     Prospector's  Handbook i2mo,  i  50 

Ande"s,  L.     Vegetable  Fats  and  Oils 8vo,  *4  oo 

—  Animal  Fats  and  Oils.     Trans,  by  C.  Salter. 8vo,  *4  oo 

—  Drying  Oils,  Boiled  Oil,  and  Solid  and  Liquid  Driers 8vo,  *5  oo 

Iron  Corrosion,  Anti-fouling  and  Anti- corrosive  Paints.     Trans,  by 

C.  Salter 8vo,  *4  oo 

Oil  Colors,  and  Printers'  Ink.     Trans,  by  A.  Morris  and  H.  Robson 

8vo,  *2  50 


D.   VAN    NOSTRAND   COMPANY'S    SHORT   TITLE   CATALOG        3 

Ande*s,  L.      Treatment   of   Paper    for    Special    Purposes.    .  Trans,    by 

C-  Salter                                  I2mo>  *2  So 

Annual  Reports  on  the  Progress  of  Chemistry. 

Vol.     I.  (1904) 8vo,  *2  00 

Vol.   II.  (1005) % 8vo,  *2  oo 

Vol.  III.  (1906) gvo,  *2  oo 

Vol.  IV.  (1907) 8vo,  *2  oo 

Vol.    V.  (1908) 8vo,  *2  oo 

Vol.  VI.  (1909) .8vo,  *2  oo 

Vol.  VII.  (1910) 8vo,  *2  oo 

Arg'and,   M.     Imaginary   Quantities.     Translated   from  the   French   by 

A.  S.  Hardy.     (Science  Series  No.  52.) i6mo,  o  50 

Armstrong,  R.,  and  Idell,  F.  E.     Chimneys  for  Furnaces  and  Steam  Boilers. 

(Science  Series  No.  i.) i6mo,  o  50 

Arnold,  E.     Armature  Windings  of  Direct-Current  Dynamos.      Trans,  by 

F.  B.  DeGress 8vo,  *2  oo 

Ashe,  S.  W.,  and  Keiley,  J.  D.     Electric  Railways.  Theoretically  and 

Practically  Treated.     Vol.  I.  Rolling  Stock i2mo,  *2  50 

Ashe,  S.  W.     Electric  Railways.     Vol.  II.  Engineering  Preliminaries  and 

Direct  Current  Sub-Stations i2mo,  *2  50 

Electricity:  Experimentally  and  Practically  Applied i2mo,  *2  oo 

Atkinson,  A.  A.     Electrical  and  Magnetic  Calculations 8vo,  *i  50 

Atkinson,  J.  J.     Friction  of  Air  in  Mines.     (Science  Series  No.  14.) . .  i6mo,  o  50 
Atkinson,  J.  J.,  and  Williams,  Jr.,  E.  H.     Gases  Met  with  in  Coal  Mines. 

(Science  Series  No.  13.) i6mo,  o  50 

Atkinson,  P.     The  Elements  of  Electric  Lighting i2mo,  i  50 

The  Elements  of  Dynamic  Electricity  and  Magnetism 12010,  2  oo 

Power  Transmitted  by  Electricity i2mo,  2  oo 

Auchincloss,  W.  S.     Link  and  Valve  Motions  Simplified 8vo,  *i  50 

Ayrton,  H.     The  Electric  Arc 8vo,  *5  oo 

Bacon,  F.  W.     Treatise  on  the  Richards  Steam-Engine  Indicator  . .  i2mo,  i  oo 

Bailes,  G.  M.     Modern  Mining  Practice.     Five  Volumes 8vo,  each,  3  50 

Bailey,  R.  D.     The  Brewers'  Analyst Svo,  *s  oo 

Baker,  A.  L.     Quaternions Svo,  *i  25 

—  Thick-Lens  Optics (In  Press.) 

Baker,  Benj.     Pressure  of  Earthwork.     (Science  Series  No.  s6.)...i6mo, 

Baker,  I.  0.     Levelling.     (Science  Series  No.  91.) i6mo,  o  50 

Baker,  M.  N.     Potable  Water.     (Science  Series  No.  61.) i6mo,  o  50 

Sewerage  and  Sewage  Purification.     (Science  Series  No.  i8.)..i6mo,  050 

Baker,  T.  T.     Telegraphic  Transmission  of  Photographs i2mo,  *i  25 

Bale,  G.  R.     Modern  Iron  Foundry  Practice.     Two  Volumes.     i2mo. 

Vol.    I.  Foundry  Equipment,  Materials  Used *2  50 

Vol.  II.  Machine  Moulding  and  Moulding  Machines *i  50 

Bale,  M.  P.     Pumps  and  Pumping i2mo,  i  53 

Ball,  R.  S.     Popular  Guide  to  the  Heavens Svo,  *4  50 

—  Natural  Sources  of  Power.     (Westminster  Series.) Svo,  *2  oo 

Ball,  W.  V.     Law  Affecting  Engineers Svo,  *3  50 

Bankson,  Lloyd.     Slide  Valve  Diagrams.     (Science  Series  No.  108.) .  i6mo,  o  50 

Barba,  J.     Use  of  Steel  for  Constructive  Purposes i2mo,  i  oo 

Barham,  G.  B.    Development  of  the  Incandescent  Electric  Lamp.  . . .  (In  Press.) 


4        D.  VAN   NOSTRAND   COMPANY'S  SHORT  TITLE  CATALOG 

Barker,  A.    Textiles  and  Their  Manufacture.     (Westminster  Series.) .  .  8vo,  2  oo 

Barker,  A.  H.     Graphic  Methods  of  Engine  Design i2mo,  *i  50 

Barnard,  F.  A.  P.     Report  on  Machinery  and  Processes  of  the  Industrial 
Arts  and  Apparatus  of  the  Exact  Sciences  at  the  Paris  Universal 

Exposition,  1867, 8vo,  5  oo 

Barnard,  J.  H.     The  Naval  Militiaman's  Guide i6mo,  leather  i  25 

Barnard,  Major  J.  G.     Rotary  Motion.     (Science  Series  No.  90.) i6mo,  o  50 

Barrus,  G.  H.     Boiler  Tests 8vo,  *a  oo 

Engine  Tests 8vo,  *4  oo 

The  above  two  purchased  together *6  oo 

Barwise,  S.     The  Purification  of  Sewage I2mo,  3  50 

Baterden,  J.  R.     Timber.     (Westminster  Series.) 8vo,  *2  oo 

Bates,  E.  L.,  and  Charlesworth,  F.     Practical  Mathematics 12010, 

Part   I.    Preliminary  and  Elementary  Course *i  50 

Part  II.    Advanced  Course *i  50 

Beadle,  C.     Chapters  on  Papermaking.     Five  Volumes i2mo,  each,  *2  oo 

Beaumont,  R.     Color  in  Woven  Design 8vo, 

--  Finishing  of  Textile  Fabrics. 8vo,  *4  oo 

Beaumont,  W.  W.     The  Steam-Engine  Indicator 8vo,  2  50 

Bedell,  F.,  and  Pierce,  C.  A.    Direct  and  Alternating  Current  Manual.Svo,  *2  oo 

Beech,  F.     Dyeing  of  Cotton  Fabrics 8vo,  *3  oo 

-  Dyeing  of  Woolen  Fabrics 8vo,  *3  50 

Beckwith,  A.     Pottery 8vo,  paper,  o  60 

Begtrup,  J.     The  Slide  Valve 8vo,  *2  oo 

Beggs,  G.  E.     Stresses  hi  Railway  Girders  and  Bridges (In  Press.) 

Bender,  C.  E.     Continuous  Bridges.     (Science  Series  No.  26.) i6mo,  o  50 

—  Proportions  of  Piers  used  in  Bridges.     (Science  Series  No.  4.) 

i6mo,  o  50 

Bennett,  H.  G.  The  Manufacture  of  Leather 8vo,  *4  50 

Bernthsen,  A.  A  Text  -  book  of  Organic  Chemistry.  Trans,  by  G. 

M'Gowan i2mo,  *2  50 

Berry,  W.  J.  Differential  Equations  of  the  First  Species.  i2mo  (In  Preparation.) 
Bersch,  J.  Manufacture  of  Mineral  and  Lake  Pigments.  Trans,  by  A.  C. 

Wright 8vo,  *5  oo 

Bertin,  L.  E.  Marine  Boilers.  Trans,  by  L.  S.  Robertson 8vo,  5  oo 

Beveridge,  J.  Papermaker's  Pocket  Book i2mo,  *4  oo 

Binns,  C.  F.  Ceramic  Technology. 8vo,  *5  oo 

—  Manual  of  Practical  Potting 8vo,  *7  50 

-  The  Potter's  Craft i2mo,  *2  oo 

Birchmore,  W.  H.     How  to  Use  a  Gas  Analysis i2mo,  *i  25 

Blaine,  R.  G.     The  Calculus  and  Its  Applications i2mo,  *i  50 

Blake,  W.  H.     Brewers'  Vade  Mecum 8vo,  *4  oo 

Blake,  W.  P.     Report  upon  the  Precious  Metals 8vo,  2  oo 

Bligh,  W.  G.     The  Practical  Design  of  Irrigation  Works 8vo,  *6  oo 

Bliicher,  H.      Modern  Industrial  Chemistry.     Trans,  by  J.  P.  Millington 

8vo,  *7  50 

Blyth,  A.  W.     Foods:  Their  Composition  and  Analysis 8vo,  7  50 

-  Poisons:  Their  Effects  and  Detection 8vo,  7  50 

Bockmann,  F.     Celluloid i2mo,  *2  50 

Bodmer,  G.  R.     Hydraulic  Motors  and  Turbines i2mo,  5  oo 

Boileau,  J.  T.     Traverse  Tables 8vo,  5  oo 


D.   VAN   NOSTRAND   COMPANY'S  SHORT  TITLE  CATALOG        5 

Bonney,  G.  E.     The  Electro-platers'  Handbook .;>  j.  4>?; . .  i2mo,  i  20 

Booth,  W.  H.     Water  Softening  and  Treatment 8vo,  *2  50 

-  Superheaters  and  Superheating  and  Their  Control. . . , 8vo,  *i  50 

Bottcher,  A.     Cranes:    Their  Construction,  Mechanical  Equipment  and 

Working.     Trans,  by  "A.  Tolhausen 4to,  *io  oo 

Bottler,  M.     Modern  Bleaching  Agents.     Trans,  by  C.  Salter i2mo,  *2  50 

Bottone,  S.  R.     Magnetos  for  Automobilists i2mo,  *i  oo 

Boulton,  S.  B.     Preservation  of  Timber.     (Science  Series  No.  82.) .  i6mo,  o  50 

Bourgougnon,  A.     Physical  Problems.     (Science  Series  No.  113:).. i6mo,  050 
Bourry,  E.     Treatise  on  Ceramic  Industries.     Trans,  by  J.  J.  Sudborough. 

8vo,  *s  oo 

Bow,  R.  H.     A  Treatise  on  Bracing 8vo,  i  50 

Bowie,  A.  J.,  Jr.     A  Practical  Treatise  on  Hydraulic  Mining 8vo,  5  oo 

Bowker,  W.  R.     Dynamo,  Motor  and  Switchboard  Circuits 8vo,  *2  50' 

Bowles,  0.     Tables  of  Common  Rocks.      (Science  Series  No.  125.). .  i6mo,  050 

Bowser,  E.  A.     Elementary  Treatise  on  Analytic  Geometry i2mo,  i  75 

—  Elementary  Treatise  on  the  Differential  and  Integral  Calculus. i2mo,  2  25 

—  Elementary  Treatise  on  Analytic  Mechanics i2mo,  3  oo 

—  Elementary  Treatise  on  Hydro- mechanics i2mo,  2  50 

— •  A  Treatise  on  Roofs  and  Bridges i2mo,  *2  25 

Boycott,  G.  W.  M.     Compressed  Air  Work  and  Diving 8vo,  *4  oo 

Bragg,  E.  M.     Marine  Engine  Design. i2mo,  *2  oo 

Brainard,  F.  R.     The  Sextant.     (Science  Series  No.  101.) i6mo, 

Brassey's  Naval  Annual  for  1911 8vo,  *6  oo 

Brew,  W.     Three-Phase  Transmission 8vo,  *2  oo 

Brewer,  R.  W.  A.     The  Motor  Car i2mo,  *2  oo 

Briggs,    R.,    and   Wolff,    A.    R.     Steam-Heating.     (Science    Series   No. 

67.) i6mo,  o  50 

Bright,  C.     The  Life  Story  of  Sir  Charles  Tilson  Bright 8vo,  *4  50 

British  Standard  Sections 8x15  *i  oo 

Complete  list  of  this  series  (45  parts)  sent  on  application. 
Broadfoot,  S.  K.     Motors,  Secondary  Batteries.     (Installation  Manuals 

Series) i2mo,  *o  75 

Broughton,  H.  H.     Electric  Cranes  and  Hoists *9  oo 

Brown,  G.     Healthy  Foundations.     (Science  Series  No.  80.) i6mo,  o  50 

Brown,  H.     Irrigation 8 vo,  *5  oo 

Brown,  Wm.  N.     The  Art  of  Enamelling  on  Metal i2mo,  * 


Handbook  on  Japanning  and  Enamelling 12 mo, 

House  Decorating  and  Painting i2mo,     * 

History  of  Decorative  Art i2mo,     * 


oo 
50 
50 
25 

00 
00 


Dipping,  Burnishing,  Lacquering  and  Bronzing  Brass  Ware. . .  i2mo, 

-  Workshop  Wrinkles 8vo, 

Browne,  R.  E.     Water  Meters.     (Science  Series  No.  81.) i6mo,      o  50 

Bruce,  E.  M.     Pure  Food  Tests i2mo,     *i  25 

Bruhns,  Dr,     New  Manual  of  Logarithms 8vo,  half  morocco,       2  50 

Brunner,  R.     Manufacture  of  Lubricants,  Shoe  Polishes  and  Leather 

Dressings.     Trans,  by  C.  Salter 8vo,     *3  oo 

Buel,  R.  H.     Safety  Valves.     (Science  Series  No.  21.) i6mo,      o  50 

Bulman,  H.  F.,  and  Redmayne,  R.  S.  A.     Colliery  Working  and  Manage- 
ment  8vo,       6  oo 

Burgh,  N.  P.     Modern  Marine  Engineering 4to,  half  morocco,     10  oo 


6        D.  VAN   NOSTRAND   COMPANY'S   SHORT  TITLE   CATALOG 

Burt,  W.  A.     Key  to  the  Solar  Compass i6mo,  leather,  2  50 

Burton,  F.  G.     Engineering  Estimates  and  Cost  Accounts i2mo,  *i  50 

Buskett,  E.  W.     Fire  Assaying i2mo,  *i  25 

Cain,  W.     Brief  Course  in  the  Calculus i2mo,  *i  75 

Elastic  Arches.     (Science  Series  No.  48.) i6mo,  o  50 

Maximum  Stresses.     (Science  Series  No.  38.) i6mo,  o  50 

• Practical  Designing  Retaining  of   Walls.     (Science  Series  No.  3.) 

i6mo,  o  50 
Theory     of     Steel-concrete     Arches    and    of    Vaulted    Structures. 

(Science  Series  No.  42.) i6mo,  o  50 

-  Theory  of  Voussoir  Arches.     (Science  Series  No.  12.) i6mo,  o  50 

Symbolic  Algebra.     (Science  Series  No.  73.) i6mo,  o  50 

Campin,  F.     The  Construction  of  Iron  Roofs 8vo,  2  oo 

Carpenter,  F.  D.     Geographical  Surveying.     (Science  Series  No.  37.) .  i6mo, 

Carpenter,  R.  C.,  and  Diederichs,  H.     Internal  Combustion  Engines. 8vo,  *5  oo 

Carter,  E.  T.     Motive  Power  and  Gearing  for  Electrical  Machinery  .  .  8vo,  *s  oo 

Carter,  H.  A.     Ramie  (Rhea),  China  Grass i2mo,  *2  oo 

Carter,  H.  R.     Modern  Flax,  Hemp,  and  Jute  Spinning 8vo,  *3  oo 

Cathcart,  W.  L.     Machine  Design.     Part  I.  Fastenings 8vo,  *3  oo 

Cathcart,  W.  L.,  and  Chaffee,  J.  I.     Elements  of  Graphic  Statics 8vo,  *3  oo 

Short  Course  in  Graphics 12010,  i  50 

Caven,  R.  M.,  and  Lander,  G.  D.     Systematic  Inorganic  Chemistry.  i2mo,  *2  oo 

Chambers'  Mathematical  Tables 8vo,  i  75 

Charnock,  G.  F.     Workshop  Practice.     (Westminster  Series.).  .  .  .8vo  (In  Press.) 

Charpentier,  P.     Timber 8vo,  *6  oo 

Chatley,  H.     Principles  and  Designs  of  Aeroplanes.    (Science   Series.) 

No.  126.) i6mo,  o  50 

How  to  Use  Water  Power i2mo,  *i  oo 

Child,  C.  T.     The  How  and  Why  of  Electricity i2mo,  i  oo 

Christie,  W.  W.     Boiler-waters,  Scale,  Corrosion,  Foaming .  .8vo,  *3  oo 

Chimney  Design  and  Theory 8vo,  *3  oo 

Furnace  Draft.     (Science  Series  No.  123.) i6mo,  o  50 

Church's  Laboratory  Guide.     Rewritten  by  Edward  Kinch 8vo,  *2  50 

Clapperton,  G.     Practical  Papermaking 8vo,  2  50 

Clark,  A.  G.     Motor  Car  Engineering.    Vol.  1.     Construction (In  Press.) 

Clark,  C.  H.     Marine  Gas  Engines i2mo,  *i  50 

Clark,  D.  K.     Rules,  Tables  and  Data  for  Mechanical  Engineers 8vo,  5  oo 

Fuel:  Its  Combustion  and  Economy i2mo,  i  50 

The  Mechanical  Engineer's  Pocketbook i6mo,  2  oo 

Tramways:  Their  Construction  and  Working 8vo,  7  50 

Clark,  J.  M.     New  System  of  Laying  Out  Railway  Turnouts i2mo,  i  oo 

Clausen-Thue,  W.     ABC  Telegraphic  Code.     Fourth  Edition i2mo,  *5  oo 

Fifth  Edition. 8vo,  *7  oo 

The  A  i  Telegraphic  Code 8vo,  *7  50 

Cleemann,  T.  M.     The  Railroad  Engineer's  Practice i2mo,  *i  50 

Clerk,  D.,  and  Idell,  F.  E.     Theory  of  the  Gas  Engine.     (Science  Series 

No.  62.) i6mo,  o  50 

Clevenger,  S.  R.     Treatise    on   the   Method   of   Government   Surveying. 

i6mo,  morocco 2  50 

Clouth,  F.     Rubber,  Gutta-Percha,  and  Balata 8vo,  *s  oo 


D     VAN    NOSTRAND   COMPANY'S  SHORT  TITLE   CATALOG       7 

Coffin,  J.  H.  C.     Navigation  and  Nautical  Astronomy f 12010,  *3  50 

Colburn,  Z.,  and  Thurston,  R.  H.     Steam  Boiler  Explosions.     (Science 

Series  No.  2.) i6mo,  o  50 

Cole,  R.  S.     Treatise  on  Photographic  Optics i2mo,  i  50 

Coles-Finch,  W.     Water,  Its  Origin  and  Use 8vo,  *s  oo 

Collins,  J.  E.     Useful  Alloys  and  Memoranda  for  Goldsmiths,  Jewelers. 

i6mo ; o  go 

Constantine,    E.     Marine    Engineers,    Their    Qualifications   and  Duties. 

8vo,  *2  oo 

Coombs,  H.  A.     Gear  Teeth.     (Science  Series  No.  120.) i6mo,  o  50 

Cooper,  W.  R.     Primary  Batteries 8vo,  *4  oo 

—  "  The  Electrician  "  Primers ..." 8vo,  *s  oo 

Part  I *!  50 

Part  II *2  50 

Part  III *2  oo 

Copperthwaite,  W.  C.     Tunnel  Shields 4to,  *p  oo 

Corey,  H.  T.     Water  Supply  Engineering 8vo  (In  Press.) 

Corfield,  W.  H.     Dwelling  Houses.     (Science  Series  No.  50.) i6mo,  o  50 

-  Water  and  Water-Supply.     (Science  Series  No.  17.) i6mo,  o  50 

Cornwall,  H.  B.     Manual  of  Blow-pipe  Analysis 8vo,  *2  50 

Courtney,  C.  F.     Masonry  Dams 8vo,  3  50 

Cowell,  W.  B.     Pure  Air,  Ozone,  and  Water i2mo,  *2  oo 

Craig,  T.     Motion  of  a  Solid  in  a  Fuel.     (Science  Series  No.  49.) i6mo,  o  50 

-  Wave  and  Vortex  Motion.     (Science  Series  No.  43.) i6mo,  o  50 

Cramp,  W.     Continuous  Current  Machine  Design 8vo,  *2  50 

Crocker,  F.  B.     Electric  Lighting.     Two  Volumes.     8vo. 

Vol.    I.     The  Generating  Plant 3  oo 

Vol.  II.     Distributing  Systems  and  Lamps 3  oo 

Crocker,  F.  B.,  and  Arendt,  M.     Electric  Motors 8vo,  *2  50 

Crocker,  F.  B.,  and  Wheeler,  S.  S.     The  Management  of  Electrical  Ma- 
chinery  i2mo,  *i  oo 

Cross,  C.  F.,  Be  van,  E.  J.,  and  Sindall,  R.  W.     Wood  Pulp  and  Its  Applica- 
tions.    (Westminster  Series.) 8vo,  *2  oo 

Crosskey,  L.  R.     Elementary  Perspective 8vo,  i  oo 

Crosskey,  L.  R.,  and  Thaw,  J.    Advanced  Perspective 8vo,  i  50 

Culley,  J.  L.      Theory  of  Arches.     (Science  Series  No.  87.) i6mo,  o  50 

Davenport,  C.     The  Book.     (Westminster  Series.)- 8vo,  *2  oo 

Da  vies,  D.  C.     Metalliferous  Minerals  and  Mining 8vo,  5  oo 

Earthy  Minerals  and  Mining 8vo,  5  oo 

Davies,  E.  H.     Machinery  for  Metalliferous  Mines 8vo,  8  oo 

Da  vies,  F.  H.    Electric  Power  and  Traction 8vo,  *2  oo 

Dawson,  P.     Electric  Traction  on  Railways 8vo,  *p  oo 

Day,  C.     The  Indicator  and  Its  Diagrams i2mo,  *2  oo 

Deerr,  N.    Sugar  and  the  Sugar  Cane 8vo,  *8  oo 

Deite,  C.     Manual  of  Soapmaking.     Trans,  by  S.  T.  King 4to,  *5  oo 

De  la  Coux,  H.    The  Industrial  Uses  of  Water.     Trans,  by  A.  Morris .  8vo,  *4  50 

Del  Mar,  W.  A.     Electric  Power  Conductors 8vo,  *2  oo 

Denny,  G.  A.     Deep-level  Mines  of  the  Rand 410,  *io  oo 

Diamond  Drilling  for  Gold *5  oo 

De  Roos,  J.  D.  C.     Linkages.     (Science  Series  No.  47.) i6mo,  o  50 


8        D.  VAN   NOSTRAND   COMPANY'S   SHORT  TITLE  CATALOG 

Derr,  W.  L.     Block  Signal  Operation Oblong  i2mo,  *i  50 

Desaint,  A.     Three  Hundred  Shades  and  How  to  Mix  Them 8vo,  *io  oo 

De  Varona,  A.     Sewer  Gases.     (Science  Series  No.  55.) i6mo,  o  50 

Devey,  R.  G.     Mill  and  Factory  Wiring.     (Installation  Manuals  Series.) 

I2H10,  *I    OO 

Dibdin,  W.  J.     Public  Lighting  by  Gas  and  Electricity 8vo,  *8  oo 

—  Purification  of  Sewage  and  Water 8vo,  6  50 

Dichmann,  Carl.     Basic  Open-Hearth  Steel  Process i2mo,  *3  50 

Dieterich,  K.     Analysis  of  Resins,  Balsams,  and  Gum  Resins 8vo,  *3  oo 

Dinger,  Lieut.  H.  C.     Care  and  Operation  of  Naval  Machinery i2mo,  *2  oo 

Dixon,  D.  B.     Machinist's  and  Steam  Engineer's  Practical  Calculator. 

i6mo,  morocco,  i  25 

Doble,  W.  A.     Power  Plant  Construction  on  the  Pacific  Coast  (In  Press.) 
Dodd,  G.     Dictionary    of    Manufactures,    Mining,    Machinery,    and    the 

Industrial  Arts i2mo,  i  50 

Dorr,  B.  F.     The  Surveyor's  Guide  and  Pocket  Table-book. 

i6mo,  morocco,  2  oo 

Down,  P.  B.     Handy  Copper  Wire  Table i6mo,  *i  oo 

Draper,  C.  H.     Elementary  Text-book  of  Light,  Heat  and  Sound. . .  i2mo,  i  oo 

Heat  and  the  Principles  of  Thermo-dynamics i2mo,  i  50 

Duckwall,  E.  W.     Canning  and  Preserving  of  Food  Products 8vo,  *s  oo 

Dumesny,  P.,  and  Noyer,  J.     Wood  Products,  Distillates,  and  Extracts. 

8vo,  *4  50 
Duncan,  W.  G.,  and  Penman,  D.     The  Electrical  Equipment  of  Collieries. 

8vo,  *4  oo 

Duthie,  A.  L.     Decorative  Glass  Processes.     (Westminster  Series.)    .8vo,  *2  oo 

Dyson,  S.  S.     Practical  Testing  of  Raw  Materials 8vo,  *s  oo 

Dyson,  S.  S.,  and  Clarkson,  S.  S.     Chemical  Works (In  Press.) 

Eccles,  R.  G.,  and  Duckwall,  E.  W.     Food  Preservatives 8vo,  paper  o  50 

Eddy,  H.  T.     Researches  in  Graphical  Statics 8vo,  i  50 

—  Maximum  Stresses  under  Concentrated  Loads 8vo,  i  50 

Edgcumbe,  K.     Industrial  Electrical  Measuring  Instruments 8vo,  *2  50 

Eissler,  M.     The  Metallurgy  of  Gold 8vo,  7  50 

—  The  Hydrometallurgy  of  Copper 8vo,  *4  50 

-  The  Metallurgy  of  Silver 8vo,  403 

The  Metallurgy  of  Argentiferous  Lead 8vo,  503 

Cyanide  Process  for  the  Extraction  of  Gold 8vo,  3  oo 

—  A  Handbook  on  Modern  Explosives 8vo,  5  oo 

Ekin,  T.  C.     Water  Pipe  and  Sewage  Discharge  Diagrams. folio,  *3  oo 

Eliot,  C.  W.,  and  Storer,  F.  H.     Compendious  Manual  of  Qualitative 

Chemical  Analysis i2mo,  *i  25 

Elliot,  Major  G.  H.     European  Light-house  Systems 8vo,  5  oo 

Ennis,  Wm.  D.     Linseed  Oil  and  Other  Seed  Oils 8vo,  *4  oo 

—  Applied  Thermodynamics 8vo  *4  50 

Flying  Machines  To-day i2mo,  *i  50 

—  Vapors  for  Heat  Engines i2mo,  *i  oo 

Erfurt,  J.     Dyeing  of  Paper  Pulp.     Trans,  by  J.  Hubner 8vo,  *7  50 

Erskine-Murray,  J.     A  Handbook  of  Wireless  Telegraphy 8vo,  *3  50 

Evans,  C.  A.     Macadamized  Roads (In  Press.) 

Ewing,  A.  J.     Magnetic  Induction  in  Iron 8vo,  *4  oo 


I  50 


D.    VAN    XOSTRAND   COMPANY'S   SHORT  TITLE   CATALOG        9 

Fairie,  J.     Notes  on  Lead  Ores i2mo,  *i  oo 

-  Notes  on  Pottery  Clays nmo, 

Fairley,  W.,  and  Andre,  Geo.  J.     Ventilation  of  Coal  Mines.     (Science 

Series  No.  58.) l6mo>  o  5o 

Fairweather,  W.  C.     Foreign  and  Colonial  Patent  Laws 8vo,  *3  oo 

Fanning,  J.  T.     Hydraulic  and  Water-supply  Engineering 8vo,  *5  oo 

Fauth,  P.      The  Moon  in  Modern   Astronomy.     Trans,  by  J.  McCabe. 

8vo,  *2  oo 

Fay,  I.  W.     The  Coal-tar  Colors 8vo,  *4  oo 

Fernbach,  R.  L.     Glue  and  Gelatine 8vo,  *3  oo 

—  Chemical  Aspects  of  Silk  Manufacture i2mo,  *i  oo 

Fischer,  E.     The  Preparation  of  Organic  Compounds.     Trans,  by  R.  V. 

Stanford i2mo,  *i  25 

Fish,  J.  C.  L.     Lettering  of  Working  Drawings Oblong  8vo,  i  oo 

Fisher,  H.  K.  C.,  and  Darby,  W.  C.     Submarine  Cable  Testing 8vo,  *3  50 

Fiske,  Lieut.  B.  A.     Electricity  in  Theory  and  Practice 8vo,  2  50 

Fleischmann,  W.    The  Book  of  the  Dairy.  Trans,  by  C.  M.  Aikman.   8vo,  4  oo 
Fleming,  J.  A.     The  Alternate-current  Transformer.     Two  Volumes.    8vo. 

Vol.    I.     The  Induction  of  Electric  Currents *5  oo 

Vol.  II.     The  Utilization  of  Induced  Currents *5  oo 

—  Propagation  of  Electric  Currents 8vo,  *3  oo 

—  Centenary  of  the  Electrical  Current , 8vo,  *o  50 

—  Electric  Lamps  and  Electric  Lighting 8vo,  *3  oo 

—  Electrical  Laboratory  Notes  and  Forms 4to,  *5  oo 

—  A  Handbook  for  the  Electrical  Laboratory  and  Testing  Room.     Two 

Volumes 8vo,  each,  *5  oo 

Fluery,  H.     The  Calculus  Without  Limits  or  Infinitesimals.     Trans,  by 

C.  0.  Mailloux (In  Press.) 

Flynn,  P.  J.     Flow  of  Water.     (Science  Series  No.  84.) i6mo,  o  50 

—  Hydraulic  Tables.     (Science  Series  No.  66.) i6mo,  o  50 

Foley,  N.     British  and  American  Customary  and  Metric  Measures .  .  folio,  *3  oo 
Foster,  H.  A.     Electrical  Engineers'  Pocket-book.     (Sixth  Edition.} 

i2mo,  leather,  5  oo 

—  Engineering  Valuations  of  Public  Utilities 8vo  (In  Press.) 

Foster,  Gen.  J.  G.     Submarine  Blasting  in  Boston  (Mass.)  Harbor.. .  .4to,  3  50 

Fowle,  F.  F.     Overhead  Transmission  Line  Crossings i2mo,  *i  50 

— -. —  The  Solution  of  Alternating  Current  Problems 8vo  (In  Press.) 

Fox,  W.  G.     Transition  Curves.     (Science  Series  No.  no.) i6mo,  o  50 

Fox,  W.,  and  Thomas,  C.  W.     Practical  Course  in  Mechanical  Draw- 
ing  I2mo,  i  25 

Foye,  J.  C.     Chemical  Problems.     (Science  Series  No.  69.) i6mo,  o  50 

—  Handbook  of  Mineralogy.     (Science  Series  No.  86.) i6mo,  o  50 

Francis,  J.  B.     Lowell  Hydraulic  Experiments 4to,  15  oo 

Freudemacher,    P.    W.     Electrical    Mining    Installations.     (Installation 

Manuals  Series  ) i2mo,  *i  oo 

Fritsch,  J.     Manufacture  of  Chemical  Manures.    Trans,  by  D.  Grant. 

8vo,  *4  oo 

Frye,  A.  I.    Civil  Engineers'  Pocket-book i2mo,  leather, 

Frye,  A.  I.     Civil  Engineers' Pocket-book ..(In  Press.) 

Fuller,  G.  W.     Investigations  into  the  Purification  of  the  Ohio  River. 4to,  *io  oo 

Furnell,  J.     Paints,  Colors,  Oils,  and  Varnishes 8vo,  *i  oo 


10     D.   VAN  NOSTRAND  COMPANY'S  SHORT  TITLE   CATALOG 

Gant,  L.  W.  Elements  of  Electric  Traction 8vo,  *2  50 

Garforth,  W.  E.  Rules  for  Recovering  Coal  Mines  after  Explosions  and 

Fires I2mo,  leather,  i  50 

Gaudard,  J.  Foundations.  (Science  Series  No.  34.) i6mo,  o  50 

Gear,  H.  B.,  and  Williams,  P.  F.  Electric  Central  Station  Distribution 

Systems 8vo,  *3  oo 

Geerligs,  H.  C.  P.  Cane  Sugar  and  Its  Manufacture 8vo,  *5  oo 

Geikie,  J.  Structural  and  Field  Geology 8vo,  *4  oo 

Gerber,  N.  Analysis  of  Milk,  Condensed  Milk,  and  Infants' Milk-Food.  8vo,  i  25 
Gerhard,  W.  P.  Sanitation,  Watersupply  and  Sewage  Disposal  of  Country 

Houses i2mo,  *2  oo 

—  Gas  Lighting.     (Science  Series  No.  in.) i6mo,  o  50 

—  Household  Wastes.     (Science  Series  No.  97.) i6mo,  o  50 

—  House  Drainage.     (Science  Series  No.  63.) i6mo,  o  50 

—  Sanitary  Drainage  of  Buildings.     (Science  Series  No.  93.) i6mo,  o  50 

Gerhardi,  C.  W.  H.     Electricity  Meters , 8vo,  *4  oo 

Geschwind,   L.     Manufacture    of   Alum   and   Sulphates.     Trans,   by   C. 

Salter 8vo,  *5  oo 

Gibbs,  W.  E.     Lighting  by  Acetylene I2mo,  *i  50 

—  Physics  of  Solids  and  Fluids.     (Carnegie  Technical  School's  Text- 

books.)   *i  50 

Gibson,  A.  H.     Hydraulics  and  Its  Application. 8vo,  *5  oo 

-  Water  Hammer  in  Hydraulic  Pipe  Lines i2mo,  *2  oo 

Gilbreth,  F.  B.     Motion  Study i2mo,  *2  oo 

Primer  of  Scientific  Management (In  Preparation.} 

Gillmore,  Gen.  Q.  A.     Limes,  Hydraulic  Cements  ard  Mortars 8vo,  4  oo 

—  Roads,  Streets,  and  Pavements i2mo,  2  oo 

Golding,  H.  A.     The  Theta-Phi  Diagram I2mo,  *i  25 

Goldschmidt,  R.     Alternating  Current  Commutator  Motor 8vo,  *3  oo 

Goodchild,  W.     Precious  Stones.     (Westminster  Series.) 8vo,  *2  oo 

Goodeve,  T.  M.     Textbook  on  the  Steam-engine i2mo,  2  oo 

Gore,  G.     Electrolytic  Separation  of  Metals . . . 8vo,  *3  50 

Gould,  E.  S.     Arithmetic  of  the  Steam-engine.  .  . .. i2mo,  i  oo 

—  Calculus.     (Science  Series  No.  112.) i6mo,  o  50 

—  High  Masonry  Dams.     (Science  Series  No.  22.) i6mo,  o  50 

—  Practical  Hydrostatics  and  Hydrostatic  Formulas.     (Science  Series 

No.  117.) i6mo,  o  50 

Grant,  J.     Brewing  and  Distilling.     (Westminster  Series.)  8vo  (In  Press.) 

Gratacap,  L.  P.    A  Popular  Guide  to  Minerals 8vo  (In  Press.) 

Gray,  J.     Electrical  Influence  Machines i2mo,  2  oo 

Greenwood,  E.     Classified  Guide  to  Technical  and  Commercial  Books.  8vo,  *3  oo 

Gregorius,  R.     Mineral  Waxes.     Trans,  by  C.  Salter 12.110,  *3  oo 

Griffiths,  A.  B.     A  Treatise  on  Manures i2mo,  3  oo 

-  Dental  Metallurgy 8vo,  *3  50 

Gross,  E.     Hops 8vo,  *4  50 

Grossman,  J.     Ammonia  and  Its  Compounds i2mo,  *i  25 

Groth,  L.  A.     Welding  and  Cutting  Metals  by  Gases  or  Electricity 8vo,  *3  oo 

Grover,  F.     Modern  Gas  and  Oil  Engines 8vo,  *2  oo 

Gruner,  A.     Power-loom  Weaving 8vo,  *3  oo 

Giildner,  Hugo.     Internal  Combustion  Engines.     Trans,  by  H.  Diederichs. 

4to,  *io  oo 


D.   VAN    NOSTRAND   COMPANY'S   SHORT  TITLE  CATALOG      11 


ci  25 


Gunther,  C.  0.     Integration '         i2mo 

Gurden,  R.  L.     Traverse  Tables folio,  half  morocco'     *y  50 

Guy,  A.  E.     Experiments  on  the  Flexure  of  Beams 8vo,     *i  25 


Haeder,    H.      Handbook   on    the 

Powles 

Hainbach,  R.     Pottery  Decoration. 

Haenig,  A. 

Hale,  W.  J. 

Hall,  C.  H. 

Hall,  R.  H. 

Hall,  W.  S. 


Steam-engine.      Trans,  by  H.  H.  P. 

i2mo, 

Trans,  by  C.  Slater i2mo, 


Emery  and  Emery  Industry 8vo, 

Calculations  of  General  Chemistry i2mo, 

Chemistry  of  Paints  and  Paint  Vehicles i2mo, 

Governors  and  Governing  Mechanism i2mo, 

Elements  of  the  Differential  and  Integral  Calculus 8vo, 

-  Descriptive  Geometry 8vo  volume  and  a  4to  atlas, 

Haller,  G.  F.,  and  Cunningham,  E.  T.     The  Tesla  Coil i2mo, 

Halsey,  F.  A.     Slide  Valve  Gears i2mo, 

-  The  Use  of  the  Slide  Rule.     (Science  Series  No.  114.) i6mo, 

-  Worm  and  Spiral  Gearing.     (Science  Series  No.  116.) i6mo, 

Hamilton,  W.  G.     Useful  Information  for  Railway  Men i6mo, 

Hammer,  W.  J.     Radium  and  Other  Radio-active  Substances 8vo, 

Hancock,  H.     Textbook  of  Mechanics  and  Hydrostatics 8vo, 

Hardy,  E.     Elementary  Principles  of  Graphic  Statics i2mo, 

Harrison,  W.  B.     The  Mechanics'  Tool-book i2mo, 

Hart,  J.  W.     External  Plumbing  Work 8vo, 

Hints  to  Plumbers  on  Joint  Wiping 8vo, 

Principles  of  Hot  Water  Supply 8vo, 

—  Sanitary  Plumbing  and  Drainage 8vo, 

Haskins,  C.  H.     The  Galvanometer  and  Its  Uses i6mo, 

Hatt,  J.  A.  H.     The  Colorist square  i2mo, 

Hausbrand,  E.     Drying  by  Means  of  Air  and  Steam.     Trans,  by   A.  C. 

Wright 12010, 

—  Evaporating,  Condensing  and  Cooling  Apparatus.     Trans,  by  A.  C. 

Wright 8vo, 

Hausner,  A.  Manufacture  of  Preserved  Foods  and  Sweetmeats.  Trans. 

by  A.  Morris  and  H.  Robson 8vo, 

Hawke,  W.  H.  Premier  Cipher  Telegraphic  Code ,4*o, 

—  100,000  Words  Supplement  to  the  Premier  Code 4to, 

Hawkesworth,  J.     Graphical  Handbook  for  Reinforced  Concrete  Design. 

4to, 
Hay,  A.     Alternating  Currents 8 vo, 

—  Electrical  Distributing  Networks  and  Distributing  Lines 8vo, 

—  Continuous  Current  Engineering 8vo, 

Heap,  Major  D.  P.     Electrical  Appliances .  8vo, 

Heaviside,  O.     Electromagnetic  Theory.     Two  Volumes 8vo,  each, 

Heck,  R.  C.  H.     The  Steam  Engine  and  Turbine 8vo, 

Steam-Engine  and  Other  Steam  Motors.     Two  Volumes. 

Vol.   I.     Thermodynamics  and  the  Mechanics 8vo, 

Vol.  II.     Form,  Construction,  and  Working 8vo, 

Notes  on  Elementary  Kinematics. . , 8vo,  boards, 

Graphics  of  Machine  Forces 8vo,  boards, 

Hedges,  K.     Modern  Lightning  Conductors 8vo, 

Heermann,  P.     Dyers' Materials.     Trans,  by  A.  C.  Wright i2mo, 


3  oo 
*3  oo 

*i  oo 

*2  00 
*2  00 
*2  25 

*3  50 

*i  25 

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0  50 

00 
00 

50 

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*3  oo 
*3  oo 
*3  oo 
*3  oo 

1  50 
*i  50 


*2    OO 

*5  oo 

*3  oo 
*5  oo 
*5  oo 

*2  50 

*2    50 

*3  50 
*2  50 

2    00 

*5  oo 
*5  oo 

*3  So 

*5  oo 


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*I    OO 

3  oo 

*2    50 


12      D.   VAN   NOSTRAND  COMPANY'S   SHORT  TITLE   CATALOG 

Hellot,  Macquer  and  D'Apligny.     Art  of  Dyeing  Wool,  Silk  and  Cotton. 

8vo,  *2  oo 

Henrici,  0.    Skeleton  Structures 8vo,  i  50 

Bering,  D.  W.     Physics  for  College  Students (In  Preparation.} 

Hering-Shaw,  A.     Domestic  Sanitation  and  Plumbing.     Two  Vols. .  .  8vo,  *s  oo 

Elementary  Science. 8vo,  *2  oo 

Herrmann,  G.     The  Graphical  Statics  of  Mechanism.     Trans,  by  A.  P. 

Smith i2mo,  2  oo 

Herzfeld,  J.     Testing  of  Yarns  and  Textile  Fabrics 8vo,  *3  50 

Hildebrandt,  A.     Airships,  Past  and  Present 8vo,  *3  50 

Hildenbrand,  B.  W.     Cable-Making.     (Science  Series  No.  32.) i6mo,  o  50 

Hilditch,  T.  P.     A  Concise  History  of  Chemistry i2mo,  *i  25 

Hill,  J.  W.     The  Purification  of  Public  Water  Supplies.      New  Edition. 

(In  Press.) 

— •—  Interpretation  of  Water  Analysis (In  Press.) 

Hiroi,  I.     Plate  Girder  Construction.     (Science  Series  No.  95.) i6mo,  o  50 

Statically-Indeterminate  Stresses i2mo,  *2  oo 

Hirshfeld,  C.  F.     Engineering  Thermodynamics.     (Science  Series  No.  45.) 

i6mo,  o  50 

Hobart,  H.  M.     Heavy  Electrical  Engineering 8vo,  *4  50 

—  Design  of  Static  Transformers i2mo,  *2  oo 

Electricity 8vo,  *2  oo 

—  Electric  Trains 8vo,  *2  50 

—  Electric  Propulsion  of  Ships 8vo,  *2  oo 

Hobbs,  W.  R.  P.     The  Arithmetic  of  Electrical  Measurements i2mo,  o  50 

Hoff,  J.  N.     Paint  and  Varnish  Facts  and  Formulas i2ino,  *i  50 

Hoff,  Com.  W.  B.     The  Avoidance  of  Collisions  at  Sea.  .  .  i6mo,  moro:co,  o  75 

Hole,  W.     The  Distribution  of  Gas 8vo,  *7  50 

Holley,  A.  L.     Railway  Practice folio,  12  oo 

Holmes,  A.  B.     The  Electric  Light  Popularly  Explained  ....  i2mo,  paper,  o  50 

Hopkins,  N.  M.     Experimental  Electrochemistry 8vo,  *3  oo 

Model  Engines  and  Small  Boats i2mo,  i  25 

Hopkinson,  J.     Shoolbred,  J.  N.,  and  Day,  R.  E.     Dynamic  Electricity. 

(Science  Series  No.  71.) i6mo,  o  50 

Homer,  J.  •  Engineers'  Turning 8vo,  *3  50 

Metal  Turning .  i2mo,  i  50 

-  Toothed  Gearing 12010,  2  25 

Houghton,  C.  E.     The  Elements  of  Mechanics  of  Materials i2mo,  *2  oo 

Houllevigue,  L.     The  Evolution  of  the  Sciences 8vo,  *2  oo 

Howe,  G.     Mathematics  for  the  Practical  Man i2mo,  *i  25 

Howorth,  J.     Repairing  and  Riveting  Glass,  China  and  Earthenware. 

8vo,  paper,  *o  50 

Hubbard,  E.     The  Utilization  of  Wood- waste 8vo,  *2  50 

Humper,  W.     Calculation  of  Strains  in  Girders i2mo,  2  50 

Humphreys,  A.  C.     The  Business  Features  of  Engineering  Practice .  8vo,  *i  25 

Hurst,  G.  H.     Handbook  of  the  Theory  of  Color 8vo,  *2  50 

—  Dictionary  of  Chemicals  and  Raw  Products 8vo,  *3  oo 

—  Lubricating  Oils,  Fats  and  Greases 8vo,  *4  oo 

—  Soaps 8vo,  *s  oo 

—  Textile  Soaps  and  Oils 8vo,  *2  50 

Hurst,  H.  E.,  and  Lattey,  R.  T.     Text-book  of  Physics 8vo,  *3  oo 


D.   VAN   NOSTRAND  COMPANY'S  SHORT  TITLE  CATALOG      13 

Hutchinson  R.  W.,  Jr.     Long  Distance  Electric  Power  Transmission .  i2mo,  *3  oo 
Hutchinson,  R.  W.,  Jr.,  and  Ihlseng,  M.  C.     Electricity  in  Mining.  .  i2mo, 

(In  Press) 

Hutchinson,  W.  B.     Patents  and  How  to  Make  Money  Out  of  Them.  i2mo,  i  25 

Button,  W.  S.     Steam-boiler  Construction 8vo,  6  oo 

Practical  Engineer's  Handbook 8vo,  7  oo 

-  The  Works'  Manager's  Handbook 8vo,  6  oo 

Hyde,  E.  W.     Skew  Arches.     (Science  Series  No.  15.) i6mo,  o  50 

Induction  Coils.     (Science  Series  No.  53.) i6mo,  o  50 

Ingle,  H.     Manual  of  Agricultural  Chemistry 8vo,  *3  oo 

Innes,  C.  H.     Problems  in  Machine  Design i2mo,  *2  oo 

Air  Compressors  and  Blowing  Engines I2mo,  *2  oo 

—  Centrifugal  Pumps i2mo,  *2  oo 

-  The  Fan i2mo,  *2  oo 

Isherwood,  B.  F.     Engineering  Precedents  for  Steam  Machinery 8vo,  2  50 

Ivatts,  E.  B.     Railway  Management  at  Stations 8vo,  *2  50 

Jacob,  A.,  and  Gould,  E.  S.     On  the  Designing  and  Construction  of 

Storage  Reservoirs.     (Science  Series  No.  6.) i6me,  o  50 

Jamieson,  A.     Text  Book  on  Steam  and  Steam  Engines 8vo,  3  oo 

—  Elementary  Manual  on  Steam  and  the  Steam  Engine i2mo,  i  50 

Jannettaz,  E.     Guide  to  the  Determination  of  Rocks.     Trans,  by  G.  W. 

Plympton , i2mo,  i  50 

Jehl,  F.     Manufacture  of  Carbons 8vo,  *4  oo 

Jennings,  A.  S.     Commercial  Paints  and  Painting.     (Westminster  Series.) 

8vo  (In  Press.) 

Jennison,  F.  H.     The  Manufacture  of  Lake  Pigments 8vo,  *3  oo 

Jepson,  G.     Cams  and  the  Principles  of  their  Construction 8vo,  *i  50 

—  Mechanical  Drawing 8vo  (In  Preparation.) 

Jockin,  W.     Arithmetic  of  the  Gold  and  Silversmith i2mo,  *i  oo 

Johnson,  G.  L.     Photographic  Optics  and  Color  Photography 8vo,  *3  oo 

Johnson,  J.  H.      Arc  Lamps  and  Accessory  Apparatus.     (Installation 

Manuals  Series.) i2mo,  *o  75 

Johnson,  T.  M.     Ship  Wiring  and  Fitting,     (Installation  Manuals  Series.) 

(In  Press.) 

Johnson,  W.  H.     The  Cultivation  and  Preparation  of  Para  Rubber . . .  8vo,  *3  oo- 

Johnson,  W.  McA.     The  Metallurgy  of  Nickel (In  Preparation.) 

Johnston,  J.  F.  W.,  and  Cameron,  C.     Elements  of  Agricultural  Chemistry 

and  Geology I2mo,  2  60 

Joly,  J.     Raidoactivity  and  Geology i2mo,  *3  oo 

Jones,  H.  C.     Electrical  Nature  of  Matter  and  Radioactivity i2mo,  *2  oo 

Jones,  M.  W.     Testing  Raw  Materials  Used  in  Paint I2mo,  *2  oo 

Jones,  L.,  and  Scard,  F.  I.     Manufacture  of  Cane  Sugar 8vo,  *5  oo- 

Joynson,  F.  H.    ,  Designing  and  Construction  of  Machine  Gearing 8vo,  2  oo 

Juptner,  H.  F.  V.     Siderology:  The  Science  of  Iron 8vo,  *5  oo 

Kansas  City  Bridge 4to,  6  oa 

Kapp,  G.     Alternate  Current  Machinery.     (Science  Series  No.  96.) .  i6mo,  o  50 

Electric  Transmission  of  Energy I2mo,  3  50 

Keim,  A.  W.     Prevention  of  Dampness  in  Buildings 8vo,  *2  oo 


14      D.  VAN   NOSTRAND   COMPANY'S  SHORT   TITLE   CATALOG 

Keller,  S.  S.     Mathematics  for  Engineering  Students.     i2mo,  half  leather. 

Algebra  and  Trigonometry,  with  a  Chapter  on  Vectors *i  75 

Special  Algebra  Edition *i  oo 

Plane  and  Solid  Geometry *i  25 

Analytical  Geometry  and  Calculus *2  oo 

Kelsey,  W.  R.     Continuous-current  Dynamos  and  Motors 8vo,  *2  50 

Kemble,  W.  T.,  and  Underbill,  C.  R.     The  Periodic  Law  and  the  Hydrogen 

Spectrum 8vo,  paper,  *o  50 

Kemp,  J.  F.     Handbook  of  Rocks 8vo,  *i  50 

Kendall,  E.     Twelve  Figure  Cipher  Code 4to,  *is  oo 

Kennedy,  A.  B.  W.,  and  Thurston,  R.  H.     Kinematics  of  Machinery. 

(Science  Series  No.  54.) i6mo,  o  50 

Kennedy,  A.  B.  W.,  Unwin,  W.  C.,  and  Idell,  F.  E.     Compressed  Air. 

(Science  Series  No.  106.) i6mo,  o  50 

Kennedy,  R.     Modern  Engines  and  Power  Generators.     Six  Volumes.   4to,  15  oo 

Single  Volumes each,  3  oo 

Electrical  Installations.     Five  Volumes 4to,  15  oo 

Single  Volumes each,  3  50 

Flying  Machines;  Practice  and  Design i2mo,  *2  oo 

Principles  of  Aeroplane  Construction .8vo,  *i  50 

Kennelly,  A.  E.     Electro-dynamic  Machinery 8vo,  i  50 

Kent,  W.     Strength  of  Materials.     (Science  Series  No.  41.) i6mo,  o  50 

Kershaw,  J.  B.  C.     Fuel,  Water  and  Gas  Analysis 8vo,  *2  50 

Electrometallurgy.     (Westminster  Series.) 8vo,  *2  oo 

The  Electric  Furnace  in  Iron  and  Steel  Production 12010,  *i  50 

Kinzbrunner,  C.     Alternate  Current  Windings 8vo,  *i  50 

Continuous  Current  Armatures 8vo,  *i  50 

-  Testing  of  Alternating  Current  Machines 8vo,  *2  oo 

Kirkaldy,  W.  G.     David  Kirkaldy's  System  of  Mechanical  Testing 4to,  10  oo 

Kirkbride,  J.     Engraving  for  Illustration 8vo,  *i  50 

Kirkwood,  J.  P.     Filtration  of  River  Waters 4to,  7  50 

Klein,  J.  F.     Design  of  a  High-speed  Steam-engine 8vo,  *5  oo 

Physical  Significance  of  Entropy 8vo,  *i  50 

Kleinhans,  F.  B.     Boiler  Construction 8vo,  3  oo 

Knight,  R.-Adm.  A.  M.     Modern  Seamanship 8vo,  *7  50 

Half  morocco *9  oo 

Knox,  W.  F.     Logarithm  Tables (In  Preparation.) 

Knott,  C.  G.,  and  Mackay,  J.  S.     Practical  Mathematics 8vo,  2  oo 

Koester,  F.     Steam-Electric  Power  Plants 4to,  *5  oo 

Hydroelectric  Developments  and  Engineering 4to,  *5  oo 

Koller,  T.     The  Utilization  of  Waste  Products 8vo,  *3  50 

Cosmetics 8vo,  *2  50 

Kretchmar,  K.     Yarn  and  Warp  Sizing 8vo,  *4  oo 

Lambert,  T.     Lead  and  its  Compounds 8vo,  *3  50 

Bone  Products  and  Manures 8vo,  *3  oo 

Lamborn,  L.  L.     Cottonseed  Products 8vo,  *3  oo 

Modern  Soaps,  Candles,  and  Glycerin 8vo,  *7  50 

Lamprecht,  R.     Recovery  Work  After  Pit  Fires.     Trans,  by  C.  Salter . .  8vo,  *4  oo 
Lanchester,  F.  W.     Aerial  Flight.     Two  Volumes.     8vo. 

Vol.   I.     Aerodynamics *6  oo 


D.   VAN   NOSTRAND  COMPANY'S  SHORT  TITLE  CATALOG      15 

Lanchester,  F.  W.     Aerial  Flight.     Vol.  II.     Aerodonetics. *6  oo 

Lamer,  E.  T.     Principles  of  Alternating  Currents I2mo,  *i  25 

Larrabee,  C.  S.     Cipher  and  Secret  Letter  and  Telegraphic  Code i6mo,  o  60 

La  Rue,  B.  F.     Swing  Bridges.     (Science  Series  No.  107.) i6mo,  o  50 

Lassar-Cohn,  Dr.     Modern  Scientific  Chemistry.     Trans,  by  M.  M.  Patti- 

son  Muir I2mO)  *2  oo 

Latimer,  L.  H.,  Field,  C.  J.,  and  Howell,  J.  W.     Incandescent  Electric 

Lighting.     (Science  Series  No.  57.) i6mo,  o  50 

Latta,  M.  N.     Handbook  of  American  Gas-Engineering  Practice 8vo,  *4  50 

American  Producer  Gas  Practice 4to,  *6  oo 

Leask,  A.  R.     Breakdowns  at  Sea I2mo,  2  oo 

-  Refrigerating  Machinery i2mo,  2  oo 

Lecky,  S.  T.  S.     "  Wrinkles  "  in  Practical  Navigation 8vo,  *8  oo 

Le  Doux,  M.     Ice-Making  Machines.     (Science  Series  No.  46.) ....  i6mo,  o  50 

Leeds,  C.  C.     Mechanical  Drawing  foi  Trade  Schools oblong  4to, 

High  School  Edition *i  25 

Machinery  Trades  Edition *2  oo 

LefSvre,  L.     Architectural  Pottery.      Trans,  by  H.  K.  Bird  and  W.  M. 

Binns 4to,  *7  50 

Lehner,  S.     Ink  Manufacture.     Trans,  by  A.  Morris  and  H.  Robson  . .  8vo,  *2  50 

Lemstrom,  S.     Electricity  in  Agriculture  and  Horticulture 8vo,  *i  50 

Le  Van,  W.  B.     Steam-Engine  Indicator.     (Science  Series  No.  78.) .  i6mo,  o  50 

Lewes,  V.  B.     Liquid  and  Gaseous  Fuels.     (Westminster  Series.).  .  .  .8vo,  *2  oo 

Lewis,  L.  P.    Railway  Signal  Engineering 8vo  (In  Press.) 

Lieber,  B.  F.     Lieber's  Standard  Telegraphic  Code 8vo,  *io  oo 

Code.     German  Edition •. 8vo,  *io  oo 

—  Spanish  Edition 8vo,  *io  oo 

French  Edition 8vo,  *io  oo 

Terminal  Index 8vo,  *2  50 

—  Lieber's  Appendix folio,  *i5  oo 

—  Handy  Tables 4to,     *2  50 

—  Bankers  and  Stockbrokers'  Code  and  Merchants  and  Shippers'  Blank 

Tables 8vo,  *i5  oo 

100,000,000  Combination  Code 8vo,  *io  oo 

—  Engineering  Code 8vo,  *i2  50 

Li  verm  ore,  V.  P.,  and  Williams,  J.     How  to  Become  a  Competent  Moior- 

man i  jmo,  *i  oo 

Livingstone,  R.     Design  and  Construction  of  Commutators 8vo,  *2  25 

Lobben,  P.     Machinists'  and  Draftsmen's  Handbook 8vo,  2  50 

Locke,  A.  G.  and  C.  G.     Manufacture  of  Sulphuric  Acid 8vo,  10  oo 

Lockwood,  T.  D.     Electricity,  Magnetism,  and  Electro-telegraph  ....  8vo,  2  50 

Electrical  Measurement  and  the  Galvanometer 12 mo,  i  50 

Lodge,  0.  J.     Elementary  Mechanics i2mo,  i  50 

—  Signalling  Across  Space  without  Wires 8vo,  *2  oo 

Lord,  R.  T.     Decorative  and  Fancy  Fabrics 8vo,  *3  50 

Loring,  A.  E.     A  Handbook  of  the  Electromagnetic  Telegraph i6mo,  o  50 

—  Handbook.     (Science  Series  No.  39.) i6mo,  o  50 

Loewenstein,  L.  C.,  and  Crissey,  C.  P.     Centrifugal  Pumps *4  50 

Lucke,  C.  E.     Gas  Engine  Design 8vo,  *3  oo 

Power  Plants:  their  Design,  Efficiency,  and  Power  Costs.     2  vols. 

(In  Preparation.) 


16      D.   VAN   NOSTRAND   COMPANY'S  SHORT  TITLE   CATALOG 

Lunge,  G.     Coal-tar  and  Ammonia.     Two  Volumes 8vo,  *i$  oo 

Manufacture  of  Sulphuric  Acid  and  Alkali.     Four  Volumes 8vo, 

Vol.     I.     Sulphuric  Acid.     In  two  parts *i5  oo 

Vol.   II.     Salt  Cake,  Hydrochloric  Acid  and  Leblanc  Soda.-     In  two 

parts *i5  oo 

Vol.  III.     Ammonia  Soda *io  oo 

Vol.  IV.   Electrolytic  Methods (In  Press.) 

-  Technical  Chemists'  Handbook i2mo,  leather,  *3  50 

-  Technical  Methods  of  Chemical  Analysis.     Trans,  by  C.  A.  Keane. 

in  collaboration  with  the  corps  of  specialists. 

Vol.   I.     In  two  parts 8vo,  *is  oo 

Vol.  H.    In  two  parts 8vo,  *i8  oo 

Vol.  HI (In  Preparation.) 

Lupton,  A.,  Parr,  G.  D.  A.,  and  Perkin,  H.     Electricity  as  Applied  to 

Mining 8vo,  *4  50 

Luquer,  L.  M.     Minerals  in  Rock  Sections 8vo,  *i  50 

Macewen,  H.  A.     Food  Inspection 8vo,  *2  50 

Mackenzie,  N.  F.     Notes  on  Irrigation  Works 8vo,  *2  50 

Mackie,  J.     How  to  Make  a  Woolen  Mill  Pay 8vo,  *2  oo 

Mackrow,  C.     Naval  Architect's  and  Shipbuilder's  Pocket-book. 

i6mo,  leather,  5  oo 

Maguire,  Wm.  R.     Domestic  Sanitary  Drainage  and  Plumbing 8vo,  4  oo 

Mallet,  A.     Compound  Engines.     Trans,  by  R.  R.  Buel     (Science  Series 

No.  10.) i6mo, 

Mansfield,  A.  N.     Electro-magnets.     (Science  Series  No.  64.) i6mo,  o  50 

Marks,  E.  C.  R.     Construction  of  Cranes  and  Lifting  Machinery.  .  .  .  i2mo,  *i  50 

—  Construction  and  Working  of  Pumps i2mo,  *i  50 

—  Manufacture  of  Iron  and  Steel  Tubes i2mo,  *2  oo 

Mechanical  Engineering  Materials i2mo,  *i  oo 

Marks,  G.  C.     Hydraulic  Power  Engineering 8vo,  353 

—  Inventions,  Patents  and  Designs.    i2mo,  *i  oo 

Marlow,  T.  G.     Drying  Machinery  and  Practice 8vo,  *s  oo 

Marsh,  C.  F.     Concise  Treatise  on  Reinforced  Concrete 8vo,  *2  50 

Marsh,  C.  F.,  and  Dunn,  W.     Reinforced  Concrete 4to,  *s  oo 

Marsh,  C.  F.,  and  Dunn,  W.     Manual  of  Reinforced  Concrete  arid  Con- 
crete Block  Construction i6mo,  morocco,  *2  50 

Marshall,  W.  J.,  and  Sankey,  H.  R.     Gas  Engines.     (Westminster  Series.) 

8vo,  *2  oo 

Martin.  G,     Triumphs  and  Wonders  of  Modern  Chemistry 8vo,  *2  oo 

Massie,  W.  W.,  and  Underbill,  C.  R.     Wireless  Telegraphy  and  Telephony. 

i2mo,  *i  oo 
Matheson,  D.     Australian  Saw-Miller's  Log  and  Timber  Ready  Reckoner. 

1 2 mo,  leather,  i  50 

Mathot,  R.  E.     Internal  Combustion  Engines 8vo,  *6  oo 

Maurice,  W.     Electric  Blasting  Apparatus  and  Explosives 8vo,  *3  50 

—  Shot  Firer's  Guide 8vo,  *i  50 

Maxwell,  J.  C.     Matter  and  Motion.     (Science  Series  No.  36.) i6mo,  o  50 

Maxwell,  W.  H.,  and  Brown,  J.  T.     Encyclopedia  of  Municipal  and  Sani- 
tary Engineering 4to,  *io  oo 

Mayer,  A.  M.     Lecture  Notes  on  Physics 8vo,  2  oo 


D.   VAN   NOSTRAND   COMPANY'S  SHORT  TITLE  CATALOG      17 

McCullough,  R.  S.     Mechanical  Theory  of  Heat » 8vo,  3  50 

Mclntosh,  J.  G.     Technology  of  Sugar 8vo,  *4  50 

—  Industrial  Alcohol 8vo,  *3  oo 

Manufacture  of  Varnishes  and  Kindred  Industries.     Three  Volumes. 

8vo. 

Vol.     I.     Oil  Crushing,  Refining  and  Boiling *3  50 

Vol.    II.     Varnish  Materials  and  Oil  Varnish  Making *4  oo 

Vol.  III.     Spirit  Varnishes  and  Materials *4  50 

McKnight,  J.  D.,  and  Brown,  A.  W.     Marine  Multitubular  Boilers.  .....  *i  50 

McMaster,  J.  B.     Bridge  and  Tunnel  Centres.     (Science  Series  No.  20.) 

i6mo,  o  50 

McMechen,  F.L.      Tests  for  Ores,  Minerals  and  Metals i2mo,  *i  oo 

McNeill,  B.     McNeiU's  Code 8vo,  *6  oo 

McPherson,  J.  A.     Water- works  Distribution 8vo,  2  50 

Melick,  C.  W.     Dairy  Laboratory  Guide I2mo,  *i  25 

Merck,  E.     Chemical  Reagents;  Their  Purity  and  Tests 8vo,  *i  50 

Merritt,  Wm.  H.     Field  Testing  for  Gold  and  Silver i6mo,  leather,  i  50 

Meyer,  J.  G.  A.,  and  Pecker,  C.  G.     Mechanical  Drawing  and  Machine 

Design 4to,  5  oo 

Michell,  S.     Mine  Drainage 8vo,  10  oo 

Mierzinski,  S.     Waterproofing  of  Fabrics.     Trans,  by  A.  Morris  and  H. 

Robson 8vo,  *2  50 

Miller,  E.  H.     Quantitative  Analysis  for  Mining  Engineers 8vo,  *i  50 

Miller,  G.  A.     Determinants.     (Science  Series  No.  105.) i6mo, 

Milroy,  M.  E.  W.     Home  Lace-making i2mo,  *i  oo 

Minifie,  W.     Mechanical  Drawing 8vo,  *4  oo 

Mitchell,  C.  A.,  and  Prideaux,  R.  M.     Fibres  Used  in  Textile  and  Allied 

Industries .^ 8vo,  *3  oo 

Modern  Meteorology I2mo,  i  50 

Monckton,  C.  C.  F.     Radiotelegraphy.     (Westminster  Series.) 8vo,  *2  oo 

Monteverde,  R.  D.     Vest  Pocket  Glossary  of  English-Spanish,  Spanish- 
English  Technical  Terms 641110,  leather,  *i  oo 

Moore,  E.  C.  S.     New  Tables  for  the  Complete  Solution  of  Ganguillet  and 

Kutter's  Formula 8vo,  *5  oo 

Morecroft,  J.  H.,  and  Hehre,  F.  W.     Short  Course  in  Electrical  Testing. 

8vo,  *i  50 

Moreing,  C.  A.,  and  Neal,  T.    New  General  and  Mining  Telegraph  Code,  8vo,  *s  oo 

Morgan,  A.  P.     Wireless  Telegraph  Apparatus  for  Amateurs i2mo,  *i  50 

Moses,  A.  J.     The  Characters  of  Crystals 8vo,  *2  oo 

Moses,  A.  J.,  and  Parsons,  C.  L.     Elements  of  Mineralogy 8vo,  *2  50 

Moss,  S.  A.  Elements  of  Gas  Engine  Design.  (Science  Series  No.i2i.)i6mo,  o  50 

-  The  Lay-out  of  Corliss  Valve  Gears.   (Science  Series  No.  119.).  i6mo,  o  50 

Mullin,  J.  P.     Modern  Moulding  and  Pattern-making i2mo,  2  50 

Munby,  A.  E.     Chemistry  and  Physics  of  Building  Materials.     (Westmin- 
ster Series.) 8vo,  *2  oo 

Murphy,  J.  G.     Practical  Mining i6mo,  i  oo 

Murray,  J.  A.     Soils  and  Manures.     (Westminster  Series.) 8vo,  *2  oo 

Naquet,  A.     Legal  Chemistry -  .  I2mo,  2  oo 

Nasmith,  J.     The  Student's  Cotton  Spinning 8vo,  3  oo 

Recent  Cotton  Mill  Construction I2mo,  2  oo 


18     D.  VAN   NOSTRAND   COMPANY'S   SHORT  TITLE   CATALOG 

Neave,  G.  B,.  and  Heilbron,  I.  M.    Identification  of  Organic  Compounds. 

1 2 mo,  *i  25 

Neilson,  R.  M.     Aeroplane  Patents 8vo,  *2  oo 

Nerz,  F.     Searchlights.     Trans,  by  C.  Rodgers 8vo,  *3  oo 

Nesbit,  A.  F.     Electricity  and  Magnetism (In  Preparation.} 

Neuberger,  H.,  and  Noalhat,  H.     Technology  of  Petroleum.     Trans,  by  J. 

G.  Mclntosh 8vo,  *io  oo 

Newall,  J.  W.     Drawing,  Sizing  and  Cutting  Bevel-gears 8vo,  i  50 

Nicol,  G.     Ship  Construction  and  Calculations 8vo,  *4  50 

Nipher,  F.  E.     Theory  of  Magnetic  Measurements i2mo,  i  oo 

Nisbet,  H.     Grammar  of  Textile  Design 8vo,  *3  oo 

Nolan,  H.     The  Telescope.     (Science  Series  No.  51.) ". i6mo,  o  50 

Noll,  A.     How  to  Wire  Buildings , i2mo,  i  50 

Nugent,  E.     Treatise  on  Optics i2mo,  i  50 

O'Connor,  H.  The  Gas  Engineer's  Pocketbook i2mo,  leather,  3  50 

Petrol  Air  Gas i2mo,  *o  75 

Ohm,  G.  S.,  and  Lockwood,  T.  D.  Galvanic  Circuit.  Translated  by 

William  Francis.  (Science  Series  No.  102.) i6mo,  o  50 

Olsen,  J.  C.  Text-book  of  Quantitative  Chemical  Analysis .8vo,  *4  oo 

Olsson,  A.  Motor  Control,  in  Turret  Turning  and  Gun  Elevating.  (U.  S. 

Navy  Electrical  Series,  No.  i.) i2mo,  paper,  *o  50 

Oudin,  M.  A.  Standard  Polyphase  Apparatus  and  Systems 8vo,  *3  oo 

Palaz,  A.     Industrial  Photometry.     Trans,  by  G.  W.  Patterson,  Jr. . .  8vo,  *4  oo 

Pamely,  C.     Colliery  Manager's  Handbook 8vo,  *io  oo 

Parr,  G.  D.  A.     Electrical  Engineering  Measuring  Instruments 8vo,  *3  50 

Parry,  E.  J.     Chemistry  of  Essential  Oils  and  Artificial  Perfumes ....  8vo,  *5  oo 

—  Foods  and  Drugs.     Two  Volumes 8vo, 

Vol.    I.     Chemical  and  Microscopical  Analysis  of  Foods  and  Drugs. 
Vol.  H.     Sale  of  Food  and  Drugs  Act 

Parry,  E.  J.,  and  Coste,  J.  H.     Chemistry  of  Pigments 8vo,  *4  50 

Parry,  L.  A.     Risk  and  Dangers  of  Various  Occupations 8vo,  *3  oo 

Parshall,  H.  F.,  and  Hobart,  H.  M.     Armature  Windings 4to,  *y  50 

Electric  Railway  Engineering 4to,  *io  oo 

Parshall,  H.  F.,  and  Parry,  E.     Electrical  Equipment  of  Tramways. .  .  .  (In  Press.} 

Parsons,  S.  J.     Malleable  Cast  Iron 8vo,  *2  50 

Partington,  J.  R.     Higher  Mathematics  for  Chemical  Students.  .i2mo,  *2  oo 

Passmore,  A.  C.     Technical  Terms  Used  in  Architecture 8vo,  *3  50 

Patterson,  D.     The  Color  Printing  of  Carpet  Yarns 8vo,  *3  50 

—  Color  Matching  on  Textiles 8vo,  *3  oo 

-  The  Science  of  Color  Mixing 8vo,  *3  oo 

Paulding,  C.  P.     Condensation  of  Steam  in  Covered  and  Bare  Pipes.  .8vo,  *2  oo 

-  Transmission  of  Heat  through  Cold-storage  Insulation i2mo,  *i  oo 

Peirce,  B.     System  of  Analytic  Mechanics 4to,  10  oo 

Pendred,  V.     The  Railway  Locomotive.     (Westminster  Series.) 8vo,  *2  oo 

Perkin,  F.  M.     Practical  Methods  of  Inorganic  Chemistry i2mo,  *i  oo 

Perrigo,  O.  E.     Change  Gear  Devices 8vo,  i  oo 

Perrine,  F.  A.  C.     Conductors  for  Electrical  Distribution 8vo,  *3  50 

Perry,  J.     Applied  Mechanics 8vo,  *2  50 

Petit,  G.     White  Lead  and  Zinc  White  Paints 8vo,  *i  50 


D.  VAN   NOSTRAND   COMPANY'S   SHORT  TITLE   CATALOG      19 

Petit,  R.     How  to  Build  an  Aeroplane.     Trans,  by  T.  O'B.  Hubbard,  and 

J.  H.  Ledeboer 8vo,  *i  50 

Pettit,  Lieut.  J.  S.     Graphic  Processes.     (Science  Series  No.  76.) . . .  i6mo,  o  50 
Philbrick,  P.  H.     Beams  and  Girders.     (Science  Series  No.  88.) . .  .  i6mo, 

Phillips,  J.     Engineering  Chemistry 8vo,  *4  50 

Gold  Assaying 8vo,  *2  50 

Dangerous  Goods 8vo,  3  50 

Phin,  J.     Seven  Follies  of  Science i2mo,  *i  25 

Pickworth,  C.  N.     The  Indicator  Handbook.     Two  Volumes. .  i2mo,  each,  i  50 

• Logarithms  for  Beginners I2mo,  boards,  o  50 

—  The  Slide  Rule i2mo,  i  oo 

Plattner's  Manual  of  Blow-pipe  Analysis.    Eighth  Edition,  revised.    Trans. 

by  H.  B.  Cornwall - .  .8vo,  *4  oo 

Plympton,  G.  W.  The  Aneroid  Barometer.  (Science  Series  No.  35.)  i6mo,  o  50 

How  to  become  an  Engineer.  (Science  Series  No.  100.) i6mo,  o  50 

Van  Nostrand's  Table  Book.  (Science  Series  No.  104.) i6mo,  o  50 

Pochet,  M.  L.  Steam  Injectors.  Translated  from  the  French.  (Science 

Series  No.  29.) i6mo,  o  50 

Pocket  Logarithms  to  Four  Places.  (Science  Series  No.  65.) ...  i6mo,  o  50 

leather,  i  oo 

Polleyn,  F.  Dressings  and  Finishings  for  Textile  Fabrics 8vo,  *3  oo 

Pope,  F.  L.  Modern  Practice  of  the  Electric  Telegraph 8vo,  i  50 

Popplewell,  W.  C.  Elementary  Treatise  on  Heat  and  Heat  Engines.  .  i2mo,  *3  oo 

Prevention  of  Smoke 8vo,  *3  50 

Strength  of  Materials 8vo,  *i  75 

Potter,  T.  Concrete 8vo,  *3  oo 

Practical  Compounding  of  Oils,  Tallow  and  Grease 8vo,  *3  50 

Practical  Iron  Founding I2mo,  i  50 

Pray,  T.,  Jr.  Twenty  Years  with  the  Indicator 8vo,  2  50 

—  Steam  Tables  and  Engine  Constant .8vo,  2  oo 

—  Calorimeter  Tables 8vo,  i  oo 

Preece,  W.  H.     Electric  Lamps (In  Press.} 

Prelini,  C.     Earth  and  Rock  Excavation 8vo,  *3  oo 

Graphical  Determination  of  Earth  Slopes 8vo,  *2  oo 

-  Tunneling.     New  Edition 8vo,  *3  oo 

—  Dredging.    A  Practical  Treatise 8vo,  *3  oo 

Prescott,  A.  B.     Organic  Analysis 8vo,  5  oo 

Prescott,  A.  B.,  and  Johnson,  0.  C.     Qualitative  Chemical  Analysis.     8vo,  *3  50 
Prescott,  A.  B.,  and  Sullivan,  E.  C.     First  Book  in  Qualitative  Chemistry. 

i2mo,  *i  50 

Pritchard,  O.  G.     The  Manufacture  of  Electric-light  Carbons .   8vo,  paper,  *o  60 
Pullen,  W.  W.  F.     Application  of  Graphic  Methods  to  the  Design  of 

Structures - I2mo>  *2  5<> 

Injectors:  Theory,  Construction  and  Working i2mo,  *i  50 

Pulsifer,  W.  H.     Notes  for  a  History  of  Lead 8vo,  4  oo 

Purchase,  W.  R.     Masonr? I2mo»  *3  oo 

Putsch,  A.     Gas  and  Coal-dust  Firing 8vo,  *3  oo 

Pynchon,  T.  R.     Introduction  to  Chemical  Physics 8vo,  3  oo 

Rafter  G.  W.     Mechanics  of  Ventilation.     (Science  Series  No.  33.) .  i6mo,  o  50 
Potable  Water.     (Science  Series  No.  103.) • l6m°.  °  So 


20      D    VAN   NOSTRAND   COMPANY'S  SHORT  TITLE  CATALOG 

Rafter,  G.  W.     Treatment  of  Septic  Sewage.     (Science  Series  No.  118.) 

i6mo,  o  50 

Rafter,  G.  W.,  and  Baker,  M.  N.     Sewage  Disposal  in  the  United  States .  4to,  *6  oo 

Raikes,  H.  P.     Sewage  Disposal  Works 8vo,  *4  oo 

Railway  Shop  Up-to-Date 4to,  2  oo 

Ramp,  H.  M.     Foundry  Practice (In  Press.) 

Randall,  P.  M.     Quartz  Operator's  Handbook i2mo,  2  oo 

Randau,  P.     Enamels  and  Enamelling 8vo,  *4  oo 

Rankine,  W.  J.  M.     Applied  Mechanics 8vo,  5  oo 

Civil  Engineering 8vo,  6  50 

Machinery  and  Millwork 8vo,  5  oo 

—  The  Steam-engine  and  Other  Prime  Movers 8vo,  5  oo 

Useful  Rules  and  Tables 8vo,  4  oo 

Rankine,  W.  J.  M.,  and  Bamber,  E.  F.     A  Mechanical  Text-book 8vo,  3  50 

Raphael,  F.  C.     Localization  of  Faults  in  Electric  Light  and  Power  Mains. 

8vo,  *3  oo 

Rathbone,  R.  L.  B.     Simple  Jewellery 8vo,  *2  oo 

Rateau,  A.     Flow  of  Steam  through  Nozzles  and  Orifices.     Trans,  by  H. 

B.  Brydon 8vo,  *i  50 

Rausenberger,  F.     The  Theory  of  the  Recoil  of  Guns .8vo,  *4  50 

Rautenstrauch,  W.     Notes  on  the  Elements  of  Machine  Design .  8 vo,  boards,  *  i  50 
Rautenstrauch,  W.,  and  Williams,  J.  T.     Machine  Drafting  and  Empirical 
Design. 

Part   I.  Machine  Drafting 8vo,  *i  25 

Part  II.  Empirical  Design (In  Preparation.) 

Raymond,  E.  B.     Alternating  Current  Engineering i2mo,  *2  50 

Rayner,  H.     Silk  Throwing  and  Waste  Silk  Spinning 8vo,  *2  50 

Recipes  for  the  Color,  Paint,  Varnish,  Oil,  Soap  and  Drysaltery  Trades .  8vo,  *3  50 

Recipes  for  Flint  Glass  Making izmo,  *4  50 

Redwood,  B.     Petroleum.     (Science  Series  No.  92.) i6mo,  o  50 

Reed's  Engineers'  Handbook 8vo,  *5  oo 

Key  to  the  Nineteenth  Edition  of  Reed's  Engineers'  Handbook .  .  8vo,  *3  oo 

—  Useful  Hints  to  Sea-going  Engineers i2mo,  i  50 

Marine  Boilers i2mo,  2  oo 

Reinhardt,  C.  W.     Lettering  for  Draftsmen,  Engineers,  and  Students. 

oblong  4to,  boards,  i  oo 

-  The  Technic  of  Mechanical  Drafting oblong  4to,  boards,  *i  oo 

Reiser,  F.     Hardening  and  Tempering  of  Steel.     Trans,  by  A.  Morris  and 

H.  Robson i2mo,  *2  05 

Reiser,  N.     Faults  in  the  Manufacture  of  Woolen  Goods.     Trans,  by  A. 

Morris  and  H.  Robson 8vo,  *2  50 

—  Spinning  and  Weaving  Calculations 8vo,  *5  oo 

Renwick,  W.  G.     Marble  and  Marble  Working 8vo,  5  oo 

Reynolds,   O.,   and  Idell,   F.   E.     Triple  Expansion  Engines.     (Science 

Series  No.  99.) i6mo,  o  50 

Rhead,  G.  F.     Simple  Structural  Woodwork " i2mo,  *i  oo 

Rice,  J.  M.,  and  Johnson,  W.  W.     A  New  Method  of  Obtaining  the  Differ- 
ential of  Functions i2mo,  o  50 

Richardson,  J.     The  Modern  Steam  Engine 8vo,  *3  50 

Richardson,  S.  S.     Magnetism  and  Electricity i2mo,  *2  oo 

Rideal,  S.    Glue  and  Glue  Testing 8vo,  *4  oo 


D.   VAN   NOSTRAND   COMPANY'S  SHORT  TITLE  CATALOG     21 

Rings,  F.     Concrete  in  Theory  and  Practice f i2mo,  *2  50 

Ripper,  W.     Course  of  Instruction  in  Machine  Drawing folio,  *6  oo 

Roberts,  F.  C.     Figure  of  the  Earth.     (Science  Series  No.  79.) i6mo,  o  50 

Roberts,  J.,  Jr.     Laboratory  Work  in  Electrical  Engineering .8vo,  *2  oo 

Robertson,  L.  S.     Water-tube  Boilers 8vo,  3  oo 

Robinson,  J.  B.     Architectural  Composition 8vo,  *2  50 

Robinson,  S.  W.     Practical  Treatise  on  the  Teeth  of  Wheels.     (Science 

Series  No.  24.) i6mo,  o  50 

Railroad  Economics.     (Science  Series  No.  59.) i6mo,  o  50 

-  Wrought  Iron  Bridge  Members.     (Science  Series  No.  60.) i6mo,  o  50 

Robson,  J.  H.     Machine  Drawing  and  Sketching 8vo,  *i  50 

Roebling,  J   A.     Long  and  Short  Span  Railway  Bridges folio,  25  oo 

Rogers,  A.     A  Laboratory  Guide  of  Industrial  Chemistry i2mo,  *i  50 

Rogers,  A.,  and  Aubert,  A.  B.     Industrial  Chemistry (In  Press.) 

Rogers,  F.     Magnetism  of  Iron  Vessels.     (Science  Series  No.  30.) .  .  i6mo,  o  50 

Rollins,  W.     Notes  on  X-Light 8vo,  *5  oo 

Rose,  J.     The  Pattern-makers'  Assistant 8vo,  2  50 

Key  to  Engines  and  Engine-running i2mo,  2  50 

Rose,  T.  K.     The  Precious  Metals.     (Westminster  Series.) 8vo,  *2  oo 

Rosenhain,  W.     Glass  Manufacture.     (Westminster  Series.) 8vo,  *2  oo 

Ross,  W.  A.     Plowpipe  in  Chemistry  and  Metallurgy i2mo,  *2  oo 

Rossiter,  J.  T.     Steam  Engines.     (Westminster  Series.). .  .  .8vo  (In  Press.) 

Pumps  and  Pumping  Machinery.     (Westminster  Series.).. 8vo  (In  Press.) 

Roth.     Physical  Chemistry 8vo,  *2  oo 

Rouillion,  L.     The  Economics  of  Manual  Training 8vo,  2  oo 

Rowan,  F.  J.     Practical  Physics  of  the  Modern  Steam-boiler 8vo,  7  50 

Rowan,   F.   J.,   and  Idell,   F.   E.     Boiler  Incrustation  and  Corrosion. 

(Science  Series  No.  27.) i6mo,  o  50 

Roxburgh,  W.     General  Foundry  Practice 8vo,  *3  50 

Ruhmer,  E.     Wireless  Telephony.     Trans,  by  J.  Erskine-Murray ....  8vo,  *3  50 

Russell,  A.     Theory  of  Electric  Cables  and  Networks 8vo,  *3  oo 

Sabine,  R.     History  and  Progress  of  the  Electric  Telegraph i2mo,  i  25 

Saeltzer  A.     Treatise  on  Acoustics i2mo,  i  oo 

Salomons,  D.     Electric  Light  Installations.     i2mo. 

Vol.    I.     The  Management  of  Accumulators ' 2  50 

Vol.  II.     Apparatus 2  25 

Vol.  III.     Applications i  50 

Sanford,  P.  G.     Nitro-explosives 8vo,  *4  oo 

Saunders,  C.  H.     Handbook  of  Practical  Mechanics i6mo,  i  oo 

leather,  i  25 

Saunnier,  C.     Watchmaker's  Handbook i2mo,  3  oo 

Sayers,  H.  M.     Brakes  for  Tram  Cars 8vo,  *i  25 

Scheele,  C.  W.     Chemical  Essays 8vo,  *2  oo 

Schellen,  H.     Magneto-electric  and  Dynamo-electric  Machines 8vo,  5  oo 

Scherer,  R.     Casein.     Trans,  by  C.  Salter 8vo,  *3  oo 

Schidrowitz,  P.     Rubber,  Its  Production  and  Industrial  Uses 8vo,  *5  oo 

Schmall,  C.  N.     First  Course  in  Analytic  Geometry,  Plane  and  Solid. 

I2mo,  half  leather,  *i  75 

Schmall,  C.  N.,  and  Shack,  S.  M.     Elements  of  Plane  Geometry ....  i2mo,  *i  25 

Schmeer,  L.     Flow  of  Water 8vo,  *3  oo 


22      D.   VAN   NOSTRAND   COMPANY'S  SHORT  TITLE  CATALOG 

Schumann,  F.     A  Manual  of  Heating  and  Ventilation i2mo,  leather,  i  50 

Schwarz,  E.  H.  L.     Causal  Geology 8vo,  *2  50 

Schweizer,  V.,  Distillation  of  Resins 8vo,  *3  50 

Scott,  W.  W.     Qualitative  Analysis.     A  Laboratory  Manual 8vo,  *i  50 

Scribner,  J.  M.     Engineers'  and  Mechanics'  Companion  .  . .  i6mo,  leather,  i  50 

Searle,  A.  B.     Modern  Brickmaking 8vo,  *5  oo 

Searle,  G.  M.     "  Sumners'  Method."     Condensed  and  Improved.    (Science 

Series  No.  124.) i6mo,  o  50 

Seaton,  A.  E.     Manual  of  Marine  Engineering 8vo,  6  oo 

Seaton,  A.  E.,  and  Rounthwaite,  H.  M.     Pocket-book  of  Marine  Engineer- 
ing  i6mo,  leather,  3  oo 

Seeligmann,  T.,  Torrilhon,  G.  L.,  and  Falconnet,  H.     India  Rubber  and 

Gutta  Percha.     Trans,  by  J.  G.  Mclntosh 8vo,  *5  oo 

Seidell,  A.     Solubilities  of  Inorganic  and  Organic  Substances 8vo,  *3  oo 

Sellew,  W.  H.     Steel  Rails 410  (In  Press.) 

Senter,  G.     Outlines  of  Physical  Chemistry i2mo,  *i  75 

Sever,  G.  F.     Electric  Engineering  Experiments 8vo,  boards,  *i  oo 

Sever,  G.  F.,  and  Townsend,  F.     Laboratory  and  Factory  Tests  in  Electrical 

Engineering 8vo,  *2  50 

Sewall,  C.  H.     Wireless  Telegraphy 8vo,  *2  oo 

Lessons  in  Telegraphy i2mo,  *i  oo 

Sewell,  T.     Elements  of  Electrical  Engineering 8vo,  *3  oo 

—  The  Construction  of  Dynamos 8vo,  *3  oo 

Sexton,  A.  H.     Fuel  and  Refractory  Materials i2mo,  *2  50 

Chemistry  of  the  Materials  of  Engineering i2mo,  *2  50 

—  Alloys  (Non- Ferrous) gvo,  *3  oo 

—  The  Metallurgy  of  Iron  and  Steel 8vo,  *6  50 

Seymour,  A.     Practical  Lithography 8vo,  *2  50 

—  Modern  Printing  Inks 8vo,  *2  oo 

Shaw,  Henry  S.  H.     Mechanical  Integrators.     (Science  Series  No.  83.) 

i6mo,  o  50 

Shaw,  P.  E.     Course  of  Practical  Magnetism  and  Electricity 8vo,  *i  oo 

Shaw,  S.     History  of  the  Staffordshire  Potteries 8vo,  *3  oo 

Chemistry  of  Compounds  Used  in  Porcelain  Manufacture 8vo,  *5  oo 

Shaw,  W.  N.      Forecasting  Weather 8vo  (In  Press.) 

Sheldon,  S.,  and  Hausmann,  E.     Electric  Traction i2mo,  *2  50 

Direct  Current  Machines i2mo,  *2  50 

Alternating  Current  Machines i2mo,  *2  50 

—  Electric  Traction  and  Transmission  Engineering 8vo,  *2  50 

Sherriff,  F.  F.     Oil  Merchants'  Manual i2mo,  *3  50 

Shields,  J.  E.     Notes  on  Engineering  Construction 12 mo,  i  50 

Shock,  W.  H.     Steam  Boilers 4to,  half  morocco,  15  oo 

Shreve,  S.  H.     Strength  of  Bridges  and  Roofs 8vo,  3  50 

Shunk,  W.  F.     The  Field  Engineer i2mo,  morocco,  2  50 

Simmons,  W.  H.,  and  Appleton,  H.  A.    Handbook  of  Soap  Manufacture. 

8vo,  *3  oo 

Simmons,  W.  H.,  and  Mitchell,  C.  A.     Edible  Fats  and  Oils 8vo,  *3  oo 

Simms,  F.  W.     The  Principles  and  Practice  of  Leveling 8vo,  2  oo 

Practical  Tunneling 8vo,  7  50 

Simpson,  G.    The  Naval  Constructor i2mo,  morocco,  *5  oo 

Sinclair,  A.     Development  of  the  Locomotive  Engine  . . .  8vo,  half  leather,  5  oo 


D.  VAN   NOSTRAND   COMPANY'S   SHORT  TITLE  CATALOG     23 

Sinclair,  A.     Twentieth  Century  Locomotive 8vo,*  half  leather,  *s  oo 

Sindall,  R.  W.     Manufacture  of  Paper.     (Westminster  Series.) 8vo,  *2  oo 

Sioane,  T.  O'C.     Elementary  Electrical  Calculations i2mo,  *2  oo 

Smith,  C.  A.  M.     Handbook  of  Testing,  MATERIALS 8vo,  *2  50 

Smith,  C.  A.  M.,  and  Warren,  A.  G.     New  Steam  Tables 8vo, 

Smith,  C.  F.     Practical  Alternating  Currents  and  Testing 8vo,  *2  50 

Practical  Testing  of  Dynamos  and  Motors 8vo,  *2  oo 

Smith,  F.  E.     Handbook  of  General  Instruction  for  Mechanics.  .  .  .i2mo,  i  50 

Smith,  J.  C.     Manufacture  of  Paint 8vo,  *3  oo 

Smith,  R.  H.     Principles  of  Machine  Work i2mo,  *3  oo 

—  Elements  of  Machine  Work i2mo,  *2  oo 

Smith,  W.     Chemistry  of  Hat  Manufacturing I2mo,  *3  oo 

Snell,  A.  T.     Electric  Motive  Power 8vo,  *4  oo 

Snow,  W.  G.     Pocketbook  of  Steam  Heating  and  Ventilation.    (In  Press.) 
Snow,  W.  G.,  and  Nolan,  T.     Ventilation  of  Buildings.     (Science  Series 

No.  5.) i6mo,  o  50 

Soddy,  F.     Radioactivity 8vo,  *3  oo 

Solomon,  M.     Electric  Lamps.     (Westminster  Series.) 8vo,  *2  oo 

Sothern,  J.  W.     The  Marine  Steam  Turbine 8vo,  *5  oo 

Soxhlet,  D.  H.     Dyeing  and  Staining  Marble.     Trans,  by  A.  Morris  and 

H.  Robson. 8vo,  *2  50 

Spang,  H.  W.     A  Practical  Treatise  on  Lightning  Protection i2mo,  i  oo 

Spangenburg,    L.     Fatigue    of    Metals.     Translated   by    S.    H.    Shreve. 

(Science  Series  No.  23.) i6mo,  o  50 

Specht,  G.  J.,  Hardy,  A.  S.,  McMaster,  J.B  .,  and  Walling.     Topographical 

Surveying.     (Science  Series  No.  72.). i6mo,  o  50 

Speyers,  C.  L.     Text-book  of  Physical  Chemistry 8vo,  *2  25 

Stahl,  A.  W.     Transmission  of  Power.     (Science  Series  No.  28.) . .  .  i6mo, 

Stahl,  A.  W.,  and  Woods,  A.  T.     Elementary  Mechanism i2mo,  *2  oo 

Staley,  C.,  and  Pierson,  G.  S.     The  Separate  System  of  Sewerage 8vo,  *3  oo 

Standage,  H.  C.     Leatherworkers'  Manual. 8vo,  *3  50 

Sealing  Waxes,  Wafers,  and  Other  Adhesives 8vo,  *2  oo 

—  Agglutinants  of  all  Kinds  for  all  Purposes i2mo,  *3  50 

Stansbie,  J.  H.     Iron  and  Steel.     (Westminster  Series.) 8vo,  *2  oo 

Steinman,  D.  B.     Suspension  Bridges  and  Cantilevers.     (Science  Series 

No.  127) o  50 

Stevens,  H.  P.     Paper  Mill  Chemist i6mo,  *2  50 

Stevenson,  J.  L.     Blast-Furnace  Calculations i2mo,  leather,  *2  oo 

Stewart,  A.     Modern  Polyphase  Machinery 12 mo,  *2  oo 

Stewart,  G.     Modern  Steam  Traps i2mo,  *i  25 

Stiles,  A.     Tables  for  Field  Engineers i2mo,  i  oo 

Stillman,  P.     Steam-engine  Indicator .' i2mo,  i  oo 

Stodola,  A.     Steam  Turbines.     Trans,  by  L.  C.  Loewenstein 8vo,  *5  oo 

Stone,  H.     The  Timbers  of  Commerce •  8vo,  3  50 

Stone,  Gen.  R.    New  Roads  and  Road  Laws i2mo,  i  oo 

Stopes,  M.     Ancient  Plants 8vo,  *2  oo 

The  Study  of  Plant  Life 8vo,  *2  oo 

Sudborough,  J.  J.,  and  James,  T.  C.     Practical  Organic  Chemistry. .  i2mo,  *2  oo 

Suffling,  E.  R.     Treatise  on  the  Art  of  Glass  Painting 8vo,  *3  50 

Swan,K.     Patents,  Designs  and  Trade  Marks.      (Westminster  Series. ).8vo,  *2  oo 

Sweet,  S.  H.     Special  Report  on  Coal .' 8vo,  3  oo 


24     D.   VAN   NO3TRAND   COMPANY'S   SHORT  TITLE    CATALOG 

Swinburne,  J.,  Wordingham,  C.  H.,  and  Martin,  T.  C.     Eletcric  Currents. 

(Science  Series  No.  109.) i6mo,  o  50 

Swoope,  C.  W.     Practical  Lessons  in  Electricity i2mo,  *2  oo 

Tailfer,  L.     Bleaching  Linen  and  Cotton  Yarn  and  Fabrics 8vo,  *5  oo 

Tate,  J.  S.     Surcharged  and  Different  Forms  of  Retaining-walls.     (Science 

Series  No.  7.) i6mo, 

Templeton,  W.     Practical  Mechanic's  Workshop  Companion. 

I2mo,  morocco,  2  oo 
Terry,  H.  L.     India  Rubber  and  its  Manufacture.     (Westminster  Series.) 

8vo,  *2  oo 

Thayer,  H.  R.     Design  of  Structures (In  Press.} 

Thiess,  J.  B.  and  Joy,  G.  A.     Toll  Telephone  Practice (In  Press.) 

Thorn,  C.,  and  Jones,  W.  H.     Telegraphic  Connections oblong  i2mo,  i  50 

Thomas,  C.  W.     Paper-makers'  Handbook (In  Press.) 

Thompson,  A.  B.     Oil  Fields  of  Russia 4to,  *7  50 

Petroleum  Mining  and  Oil  Field  Development 8vo,  *5  oo 

Thompson,  E.  P.     How  to  Make  Inventions 8vo,  o  50 

Thompson,  S.  P.     Dynamo  Electric  Machines.     (Science  Series  No.  75.) 

i6mo,  o  50 

Thompson,  W.  P.     Handbook  of  Patent  Law  of  All  Countries i6mo,  i  50 

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Tidy,  C.   Meymott.     Treatment  of  Sewage.     (Science   Series  No.   94.). 

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Turrill,  S.  M.     Elementary  Course  in  Perspective i2mo,  *i  25 

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Villon,  A.  M.     Practical  Treatise  on  the  Leather  Industry.     Trans,  by  F. 

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Volk,  C.  Haulage  and  Winding  Appliances 8vo,  *4  oo 

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C.  Salter 8vo,  *4  50 

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Vose,  G.  L.     Graphic  Method  for  Solving  Certain  Questions  in  Arithmetic 

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Waring,  Jr.,  G.  E.     Sanitary  Conditions.     (Science  Series  No.  31.).  •  i6mo,  o  50 
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Watkins,  A.    Photography.     (Westminster  Series.) 8vo,  *2  oo 

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Weale,  J.     Dictionary  of  Terms  Used  in  Architecture i2mo,  2  50 

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Webber,  W.  H.  Y.     Town  Gas.     (Westminster  Series.) 8vo,  *2  oo 

Weisbach,  J.     A  Manual  of  Theoretical  Mechanics 8vo,  *6  oo 

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Weisbach,  J.,  and  Herrmann,  G.     Mechanics  of  Air  Machinery 8vo,  *3  75 

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Wilcox,  R.  M.     Cantilever  Bridges.     (Science  Series  No.  25.) i6mo,  o  50 

Wilkinson,  H.  D.     Submarine  Cable  Laying  and  Repairing 8vo,  *6  oo 

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Williamson,  R.  S.     On  the  Use  of  the  Barometer 4to,  15  oo 

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Winkler,  C.,  and  Lunge,  G.     Handbook  of  Technical  Gas- Analysis . .  .8vo,  4  oo 

Winslow,  A.     Stadia  Surveying.     (Science  Series  No.  77.) i6mo,  o  50 

Wisser,   Lieut.   J.   P.     Explosive  Materials.     (Science   Series  No.   70.). 

i6mo,  o  50 

Wisser,  Lieut.  J.  P.     Modern  Gun  Cotton.     (Science  Series  No.  89.)  i6mo,  o  50 

Wood,  De  V.     Luminiferous  Aether.     (Science  Series  No.  85.) ....  i6mo,  o  50 
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Worden,  E.  C.     The  Nitrocellulose  Industry.     Two  Volumes 8vo,  *io  oo 

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Wright,  T.  W.     Elements  of  Mechanics 8vo,  *2  50 

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D.   VAN  NOSTRAND  COMPANY'S    SHORT  TITLE  CATALOG    27 
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Zeuner,  A.     Technical  Thermodynamics.     Trans,  by  J.  F.  Klein.     Two 

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ELECTRICAL  ENGINEER'S 
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